Evaporative fuel vapor emission control systems

ABSTRACT

The present disclosure describes an evaporative emission control canister system that includes: one or more canisters comprising at least one vent-side particulate adsorbent volume comprising a particulate adsorbent having microscopic pores with a diameter of less than about 100 nm; macroscopic pores having a diameter of about 100-100,000 nm; and a ratio of a volume of the macroscopic pores to a volume of the microscopic pores that is greater than about 150%, and having a retentivity of about 1.0 g/dL or less. The system may further include a high butane working capacity adsorbent. The disclosure also describes a method for reducing emissions in an evaporative emission control system.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent Application62/521,912 filed 19 Jun. 2017, and U.S. Provisional Patent Application62/685,174 filed 14 Jun. 2018, the contents of which are incorporatedherein by reference in their entirety for all purposes.

BACKGROUND 1. Field of the Discovery

The present disclosure generally relates to a system comprisingparticulate adsorbent material and methods of using the same. Moreparticularly, the present disclosure relates to a system comprising alow retentivity particulate adsorbent material and methods of using thesame in evaporative fuel vapor emission control systems.

2. Background Information

Evaporation of gasoline fuel from motor vehicle fuel systems is a majorsource of hydrocarbon air pollution. Such emissions can be controlled bythe canister systems that employ activated carbon to adsorb the fuelvapor generated by the fuel systems. Under certain modes of engineoperation, the adsorbed fuel vapor is periodically removed from theactivated carbon by purging the canister systems with ambient air todesorb the fuel vapor from the activated carbon. The regenerated carbonis then ready to adsorb additional fuel vapor.

An increase in environmental concerns has continued to drive strictregulations of the hydrocarbon emissions from motor vehicles even whenthe vehicles are not operating. The vapor pressure in a vehicle fueltank will increase as the ambient temperature increases while thevehicle is parked. Normally, to prevent the leaking of the fuel vaporfrom the vehicle into the atmosphere, the fuel tank is vented through aconduit to a canister containing suitable fuel adsorbent materials thatcan temporarily adsorb the fuel vapor. A mixture of fuel vapor and airfrom the fuel tank enters the canister through a fuel vapor inlet of thecanister and expands or diffuses into the adsorbent volume where thefuel vapor is adsorbed in temporary storage and the purified air isreleased to the atmosphere through a vent port of the canister. Once theengine is turned on, ambient air is drawn into the canister system viamanifold vacuum through the vent port of the canister. The purge airflows through the adsorbent volume inside the canister and desorbs thefuel vapor adsorbed on the adsorbent volume before entering the internalcombustion engine through a fuel vapor purge conduit. The purge air doesnot desorb the entire fuel vapor adsorbed on the adsorbent volume,resulting in a residue hydrocarbon (“heel”) that may be emitted to theatmosphere. In addition, that heel in local equilibrium with the gasphase also permits fuel vapors from the fuel tank to migrate through thecanister system as emissions. Such emissions typically occur when avehicle has been parked and subjected to diurnal temperature changesover a period of several days, commonly called “diurnal breathinglosses.”

In the US, the California Low Emission Vehicle Regulations made itdesirable for the diurnal breathing loss (DBL) emissions from thecanister system to be below about 20 mg (“PZEV”) for a number ofvehicles beginning with the 2003 model year and below about 50 mg,(“LEV-II”) for a larger number of vehicles beginning with the 2004 modelyear. Now the California Low Emission Vehicle Regulation (LEV-III) andEPAs Tier 3 Standard requires canister DBL emissions not to exceed 20 mgas per the Bleed Emissions Test Procedure (BETP) as written in theCalifornia Evaporative Emissions Standards and Test Procedures for 2001and Subsequent Model Motor Vehicles, 22 Mar. 2012 and EPAs Control ofAir Pollution From Motor Vehicles: Tier 3 Motor Vehicle Emission andFuel Standards; Final Rule, 40 CFR Parts 79, 80, 85 et al. Globally, bycontrast, evaporative emission regulations have been less stringent thanin the US, but the trend is now for more stringent regulations, alongthe path that the US has taken. There is increased recognition of thebenefits from tighter controls for better use of vehicle fuel and forcleaner air, especially in regions where light duty vehicle use isgrowing rapidly and air quality issues require urgent attention.

In order to meet the evaporative fuel emission regulatory standards inthe vehicle design stage, vehicle manufacturers typically providepotential suppliers with target specifications on overall canistersystem performance, in terms of functional content, appearance, physicalcharacteristics, and durability, hence leaving appropriate designflexibility for achieving those targets to the canister systemmanufacturers. For example, General Motors Corporation sets many designspecifications for evaporative emission control canister systems (SeeGMW16494). A notable specification is the total allowable pressure dropof a carbon canister system. In this example, the maximum flowrestriction for a canister system intended for on-board refueling vaporrecovery (ORVR) “shall be 0.90±0.225 kPa at 60 liter/min (lpm) air flow. . . as measured at the tank tube while flowing air from the canistertank tube to the fresh air tube” (see Section 3.2.1.3.2.2 of GMW-16494).This specification and others in GMW-16494 offer examples of the degreethat vehicle manufacturer allow for flow restriction.

As a result of such specifications, canister system designers appreciatea wide array of adsorbent options because, in addition to varied fuelemissions regulations around the world, the demands are quite variedacross different vehicle platforms from different vehicle manufacturersper engine type, engine operational design, space availability, purgeavailability, and canister system control strategy. Certainly, “one sizedoes not fit all” for canister system design and its adsorbent fills.Accordingly, new adsorbent options and approaches for balancing thetradeoffs in terms of cost, size, flow restriction, working capacity,diurnal breathing loss (DBL) performance, complexity, and placementflexibility, are in high demand.

For example, several approaches involving chamber design and adsorbentproperties have been reported for reducing DBL emissions which is one ofthe specification aspects that the canister system must meet.

One approach for attaining low emissions is to significantly increasethe volume of purge gas to enhance desorption of the residue hydrocarbonheel from the adsorbent volume. This approach, however, has the drawbackof complicating management of the fuel/air mixture to the engine duringthe purge step and tends to adversely affect tailpipe emissions. SeeU.S. Pat. No. 4,894,072. For certain high performance and high fuelefficiency engine designs, including turbo-charged, gasoline directinjection, and hybrid electric vehicles, such high purge is notavailable or might greatly affect engine performance.

Another approach is to design the canister to have a relatively lowcross-sectional area on the vent-side of the canister, either by theredesign of existing canister dimensions or by the installation of asupplemental vent-side canister chamber of appropriate dimensions. SeeU.S. Pat. No. 5,957,114. This approach reduces the residual hydrocarbonheel by increasing the intensity of purge air. One drawback of suchapproach is that the relatively low cross-sectional area imparts anexcessive flow restriction to the canister for solid-shaped conventionalparticulate adsorbents of 1-3 mm diameter, except for the shortest bedlength which then otherwise compromises the effectiveness of thisvent-side chamber for DBL emission control. Therefore, thoughpotentially effective for reducing bleed emissions of the system, theexcessive flow restriction is not accommodated by conventionalparticulate adsorbent.

An additional approach for increasing the purge efficiency is to heatthe purge air, or a portion of the adsorbent volume having adsorbed fuelvapor, or both. See U.S. Pat. Nos. 6,098,601 and 6,279,548. However,this approach increases the complexity of control system management andposes some safety concerns.

Still another approach is in the selection of multiple adsorbents in thecanister system chambers, such as to route the fuel vapor through one ormore fuel-side adsorbent volumes, which are located proximal to or nearthe fuel side port of the canister system (i.e., are upstream in thefluid or vapor path), and then to at least one vent-side or subsequentadsorbent volume, which is located downstream in the fluid or vapor path(or distal) relative to the fuel-side adsorbent, prior to venting to theatmosphere, wherein the initial adsorbent volume has a higherincremental adsorption capacity (greater slope in the butane adsorptionisotherm between 5 and 50% concentrations) than the subsequent adsorbentvolume. See U.S. Pat. No. RE38,844 and U.S. Pat. No. 9,732,649, whichare incorporated herein by reference in their entirety.

One effective format for a subsequent adsorbent volume towards thevent-side of the canister system is an elongated, ceramic-boundactivated carbon honeycomb, such as Nuchar® HCA (Ingevity®, NorthCharleston, S.C., USA), typically available in diameters of 29, 35 and41 mm and certain lengths between 50 and 200 mm. While such an adsorbentstructure provides the desired adsorptive properties with low flowrestriction, these engineered parts are costly to make, requiringspecial skill and equipment to manufacture, and the immediate initialcustomer, the designer of canister systems, is limited to only thosesize honeycomb parts that are normally available for system design,testing and certification.

An alternative effective format for a vent-side volume that allowsflexibility in chamber design is in 2-3 mm pellet form, e.g., Nuchar®BAX LBE grade activated carbon (Ingevity®, North Charleston, S.C., USA)or 2GK-C7 grade activated carbon (Kuraray Chemical Co., Ltd., Bizen-shi,Japan). While these pellets may have useful adsorptive properties forbleed emission control and, as a particulate material, allow greatflexibility for the adsorbent chamber dimensions into which thesepellets are filled, these pellets have high flow restriction propertiesrelative to carbon honeycombs, which limits potentially useful lowcross-sectional area geometries as taught by U.S. Pat. No. 5,957,114.

Along the concept of adsorbents-in-series, adsorbent volumes with agradation in adsorption working capacity, e.g., butane working capacity(BWC), and gram-total butane working capacity on the vent-side of thesystem are taught to be particularly useful for emission controlcanister systems when operated under a low volume of purge, such as for“hybrid” vehicles, where the internal combustion engine is turned offnearly half of the time during vehicle operation and where the purgefrequency is much less than normal. See WO 2014/059190(PCT/US2013/064407). Other engine designs which pose challenges forcanister system purging include features of gasoline direct injectionand turbo-charge or turbo-assist. However, these approaches aretypically limited to the carbon honeycomb format.

The challenge and desire described by the above approaches, and others(see, e.g., U.S. Pat. Nos. 7,186,291 and 7,305,974), is to diminish thedetrimental effect of the residual adsorbed vapors on evaporativeemission canister system performance, especially the DBL emissionsperformance, where the least amount of retained adsorbed vapors (lowestamount of heel) is highly sought. Furthermore, the deterioration of DBLemission performance, and working capacity performance of canistersystems (also called “ageing”) is also known to be due to accumulationsof less purgeable components in this adsorbed vapor heel (see, e.g., SAETechnical Paper Series 2000-01-895). Therefore, the benefit of lowretention of hydrocarbons after purge is twofold: a low level of DBLemissions for the new vehicle, and the maintenance of working capacityand emissions performance over the life of the vehicle as afforded bylow vapor retention properties.

While highly desirable as an approach, the combination of low cost, lowcomplexity of production, high material structural strength, low flowrestriction, and lowest vapor retention as engendered by a particulateadsorbent for evaporative emissions control is taught to be a nearlyinsurmountable design challenge. For example, as taught by U.S. Pat. No.9,174,195 (“the '195 patent”), the useful range for the ratio ofmacroscopic, “M”, to microscopic, “m”, pore volumes is limited tobetween 65% and 150% M/m, because of mechanical strength failing athigher ratio. Furthermore, within the claimed pore ratio range, thevapor retention (retentivity) is asymptotic, to greater than 1 g/dLmeasured as the residual amount of butane by a standard ASTM test, andgreater than the noted 1.7 g/dL target when the pore ratio was beyondthe claimed 150% limit (in addition to poor strength). It is importantto note that the '195 patent teaches that at a typical 5 mm diameterpellet having an M/m pore ratio of over 150% is not robust enough foruse (see FIG. 6). The tradeoff between pore ratio and pellet strength isunderscored by the 2GK-C7 pellet adsorbent material (Kuraray ChemicalCo., Ltd., Bizen-shi, Japan), which despite having an M/m of about 170%had a 2.6 mm mean diameter, which while improving its strength has theunwanted effect of increasing flow restriction. In other words, despiteits functionality for controlling emissions, the '195 patent teachesthat the relatively higher M/m ratio of 2GK-C7 is unsuitable for largerdiameter pellets, which while providing for lower flow restriction wouldalso have impaired strength, and relatively high retentivity.

Accordingly, there remains a need for additional adsorbent options fordesigners of evaporative emission control systems, particularly for theadsorbent volumes towards the vent-side that are robust but alsodemonstrate low vapor retention, and low flow restriction, which helpachieve high working capacity and low DBL emissions performance by thesystem over the life of the vehicle.

SUMMARY

Presently described are evaporative emission control canister systemswith surprising and unexpected characteristics, including two-daydiurnal breathing loss (DBL) emissions of less than about 50 mg or lessthan about 20 mg, including in instances with relatively low volumes ofpurge (e.g., less about 175 BV or less than 100 BV). It was surprisinglyand unexpectedly discovered that low purge and low DBL evaporativeemission control canister systems are possible with particulateadsorbent volumes as described herein, which are cost effective tomanufacture, possess desirable retentivity, have high materialstructural strength, and low flow restriction. For example, theparticulate adsorbent materials, which provide low DBL canister systemsas described herein have a macroporisity (M) to microporosity (m) ratio(i.e., M/m) of above 150%, butane retentivity below 1.0 g/dL while alsobeing sufficiently large and robust enough to be utilized in the systemwithout imposing excessive flow restriction.

Thus, in one aspect, the disclosure provides an evaporative emissioncontrol canister system comprising: one or more canisters having aplurality of chambers, each defining a volume, which are in fluidcommunication allowing a fluid (e.g., air, gas or fuel vapor) to flowdirectionally from one chamber to the next, wherein at least one chambercomprises at least one particulate adsorbent volume that includes aparticulate adsorbent having microscopic pores with a diameter of lessthan about 100 nm, macroscopic pores having a diameter of about100-100,000 nm, and a ratio of a volume of the macroscopic pores to avolume of the microscopic pores that is greater than about 150%, andwherein the particulate adsorbent volume has a flow restriction propertyof less than 40 Pa/cm under conditions of 46 cm/s apparent linear airflow velocity applied to a 43 mm diameter bed of the particulateadsorbent material or a flow restriction of less than 0.3 kPa under 40lpm air flow or both. In certain embodiments, the particulate adsorbentvolume has a length to diameter ratio of 2 or more, butane retentivityof <1.0 g/dL, or a combination thereof. In certain embodiments, thebutane retentivity is <0.5 g/dL. In certain embodiments, the evaporativeemission control canister system comprises at least one fuel-sideadsorbent volume, at least one vent-side subsequent adsorbent volume orboth. In certain embodiments, the adsorbent volumes are located within asingle canister or within a plurality of canisters that are connected topermit sequential contact by the fuel vapor. In certain embodiments, theat least one particulate adsorbent volume, the at least one fuel-sideadsorbent volume or both have a nominal butane working capacity (BWC) ofat least 8 g/dL (e.g., at least 10 g/L), a nominal incrementaladsorption capacity (IAC) at 25° C. of at least 35 g/L between vaporconcentrations of 5 vol % and 50 vol % n-butane, or both. In certainembodiments, the at least one particulate adsorbent volume, the at leastone vent-side subsequent adsorbent volume or both have a nominal BWC ofless than 8 g/dL, a nominal IAC at 25° C. of less than 35 g/L betweenvapor concentrations of 5 vol % and 50 vol % n-butane, or both. Incertain embodiments, the particulate volume has an M/m ratio that isgreater than about 200%.

In an additional aspect, the description provides an evaporativeemission control canister system including one or more canisterscomprising at least one fuel-side adsorbent volume (i.e., adsorbentvolume at or near the fuel tank vapor inlet), and at least one vent-sideparticulate adsorbent volume. In certain embodiments, the at least onevent-side particulate adsorbent volume is included as an alternative toor in combination with one or more vent-side subsequent adsorbentvolumes. The at least one fuel-side adsorbent volume, the at least onevent-side particulate adsorbent volume, and/or the at least onevent-side subsequent adsorbent volume can be contained either in asingle canister or in separate canisters that are connected to permitsequential contact by fuel vapor (and conversely, purge air). In certainembodiments, the at least one vent-side subsequent adsorbent volumeincludes a non-particulate adsorbent material, e.g., a foam, monolith, apolymer or paper sheet, or honeycomb (e.g., activated carbon honeycomb),wherein the at least one vent-side subsequent adsorbent volume imposeslow vapor or fluid flow restriction.

In certain embodiments, the evaporative emission control canister systemcomprises: at least one vent-side subsequent adsorbent volume that isupstream of the at least one vent-side particulate adsorbent volume(i.e., located closer to the fuel-side adsorbent volume or fuel vaporinlet in the fluid path), at least one vent-side subsequent adsorbentvolume that is downstream of the at least one vent-side particulateadsorbent volume (i.e., located closer to the vent port in the fluidpath), or a combination thereof.

In certain embodiments, the evaporative emission control canister systemcomprises: at least one vent-side particulate adsorbent volume that isupstream of the at least one vent-side subsequent adsorbent volume(i.e., located closer to the fuel-side adsorbent volume or fuel vaporinlet in the fluid path), at least one vent-side particulate adsorbentvolume that is downstream of the at least one vent-side subsequentadsorbent volume (i.e., located closer to the vent port in the fluidpath), or a combination thereof.

In any of the aspects or embodiments described herein, the at least onevent-side subsequent adsorbent volume includes a non-particulateadsorbent material, e.g., a foam, monolith, honeycomb, polymer or papersheet. In certain embodiments, the non-particulate adsorbent materialimposes low vapor or fluid flow restriction. In certain embodiments, thenon-particulate adsorbent material is a honeycomb with uniformcross-sectional area.

The adsorbents suitable for use in the adsorbent volumes may be derivedfrom many different materials and in various forms. It may be a singlecomponent or a blend of different components. Furthermore, the adsorbent(either as a single component or a blend of different components) mayinclude a volumetric diluent. Non-limiting examples of the volumetricdiluents may include, but are not limited to, spacer, inert gap, foams,fibers, springs, or combinations thereof.

In any of the aspects or embodiments described herein, any knownadsorbent materials may be used for the fuel-side adsorbent volume,vent-side particulate adsorbent volume, and vent-side subsequentadsorbent volume, including, but not limited to, activated carbon,carbon charcoal, zeolites, clays, porous polymers, porous alumina,porous silica, molecular sieves, kaolin, titania, ceria, or combinationsthereof. Activated carbon may be derived from various carbon precursors.By way of non-limiting example, the carbon precursors may be wood, wooddust, wood flour, cotton linters, peat, coal, coconut, lignite,carbohydrates, petroleum pitch, petroleum coke, coal tar pitch, fruitpits, fruit stones, nut shells, nut pits, sawdust, palm, vegetables suchas rice hull or straw, synthetic polymer, natural polymer,lignocellulosic material, or combinations thereof. Furthermore,activated carbon may be produced using a variety of processes including,but are not limited to, chemical activation, thermal activation, orcombinations thereof.

In any of the aspects or embodiments described herein, any variety ofadsorbent forms may be used for the fuel-side adsorbent volume,vent-side particulate adsorbent volume, and vent-side subsequentadsorbent volume. Non-limiting examples of the adsorbent forms mayinclude granular, pellet, spherical, honeycomb, monolith, pelletizedcylindrical, particulate media of uniform shape, particulate media ofnon-uniform shape, structured media of extruded form, structured mediaof wound form, structured media of folded form, structured media ofpleated form, structured media of corrugated form, structured media ofpoured form, structured media of bonded form, non-wovens, wovens, sheet,paper, foam, or combinations thereof. The adsorbent (either as a singlecomponent or a blend of different components) may include a volumetricdiluent. Non-limiting examples of the volumetric diluents may include,but are not limited to, spacer, inert gap, foams, fibers, springs, orcombinations thereof. Furthermore, the adsorbents may be extruded intospecial thin-walled cross-sectional shapes, such as hollow-cylinder,star, twisted spiral, asterisk, configured ribbons, or other shapeswithin the technical capabilities of the art. In shaping, inorganicand/or organic binders may be used.

The honeycomb adsorbents may be in any geometrical shape including, butare not limited to, round, cylindrical, or square. Furthermore, thecells of honeycomb adsorbents may be of any geometry. Honeycombs ofuniform cross-sectional areas for the flow-through passages, such assquare honeycombs with square cross-sectional cells or spiral woundhoneycombs of corrugated form, may perform better than round honeycombswith square cross-sectional cells in a right angled matrix that providesadjacent passages with a range of cross-sectional areas and thereforepassages that are not equivalently purged. Without being bound by anytheory, it is believed that the more uniform cell cross-sectional areasacross the honeycomb faces, the more uniform flow distribution withinthe part during both adsorption and purge cycles, and, therefore, lowerDBL emissions from the canister system.

In some embodiments, the evaporative emission control system may furtherinclude one or more heat input unit(s) for heating one or more adsorbentvolume(s) and/or one or more empty volume(s). The heat input units mayinclude, but are not limited to, internal resistive elements, externalresistive elements, or heat input units associated with the adsorbent.The heat input unit associated with the adsorbent may be an elementseparate from the adsorbent (i.e., non-contacted with adsorbents).Alternatively, the heat input unit associated with the adsorbent may bea substrate or layer on to which the adsorbent is attached, bonded,non-bonded, or in physical contact. The heat input unit associated withthe adsorbent may be adsorbent directly heated electrically by havingappropriate resistivity. The resistivity properties of the adsorbent maybe modified by the addition of conductive or resistive additives andbinders in the original preparation of the adsorbent and/or in theforming of the adsorbent into particulate or monolithic forms. Theconductive component may be conductive adsorbents, conductivesubstrates, conductive additives and/or conductive binders. Theconductive material may be added in adsorbent preparation, added inintermediate shaping process, and/or added in adsorbent shaping intofinal form. Any mode of heat input unit may be used. By way ofnon-limiting example, the heat input unit may include a heat transferfluid, a heat exchanger, a heat conductive element, and positivetemperature coefficient materials. The heat input unit may or may not beuniform along the heated fluid path length (i.e., provide differentlocal intensities). Furthermore, the heat input unit may or may not bedistributed for greater intensity and duration of heating at differentpoints along the heated fluid path length.

In certain embodiments, the vent-side subsequent adsorbent volume is anactivated carbon monolith or activated carbon honeycomb, and is locatedupstream in the fuel vapor path relative to the location of thevent-side particulate adsorbent volume, downstream in the fuel vaporpath relative to the location of the vent-side particulate adsorbentvolume or a combination thereof.

In certain embodiments, the at least one fuel-side adsorbent volume hasat least one of a relatively high butane working capacity (BWC), aneffective incremental adsorption capacity of above about 35 gramsn-butane per liter (g/L) between vapor concentration of 5 vol % and 50vol % n-butane, or both. For example, in certain embodiments, the systemfurther comprises at least one additional high butane working capacity(BWC) adsorbent volume that is located upstream from or prior to avent-side particulate adsorbent volume (i.e., the high butane workingcapacity adsorbent volumes come into contact with the fuel vapor beforethe vent-side particulate adsorbent volume while the vehicle is atrest). In certain embodiments, the fuel-side adsorbent volume has atleast one of: i) a relatively high butane working capacity (BWC), e.g.,greater than 8, 9, 10, 11, 12, 13, 14, 15 or more grams per deciliter(g/dL), ii) an incremental adsorbent capacity of greater than 35, 40,45, 50, 55, 60, 65, 70, 75, 80, 85, 90 or more grams n-butane per liter(g/L) between vapor concentration of 5 vol % and 50 vol % n-butane, orboth.

In certain embodiments, the evaporative emission control canister systemcomprises at least one vent-side particulate adsorbent volume (i.e.,downstream relative to the at least one fuel-side adsorbent volume inthe vapor path from the fuel tank to vent port). In certain embodiments,the at least one vent-side particulate adsorbent volume has a low butaneretentivity, a relatively high ratio of macroscopic size pore volume tomicroscopic pore volume (M/m), and relatively low flow restrictionproperties. In certain embodiments, the particulate adsorbent with lowbutane retentivity and low flow restriction properties has microscopicpores with a diameter of less than about 100 nm, macroscopic poreshaving a diameter of about 100-100,000 nm and a ratio of a volume of themacroscopic pores to a volume of the microscopic pores (M/m) that isgreater than about 150%, 160%, 170%, 180%, 190%, 200%, 210%, or 220% ormore, wherein the particulate adsorbent material has a retentivity ofabout 1.0 g/dL or less and flow restriction of less than less than 40Pa/cm pressure drop under 46 cm/s apparent linear gas flow velocity.

In any of the aspects or embodiments described herein, the vent-sideparticulate adsorbent volume has a flow restriction of less than about0.3 kPa under 40 lpm air flow.

In any of the aspects or embodiments described herein the at least onevent-side particulate adsorbent volume has a length to diameter ratio ofabout 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5 or greater. Incertain embodiments, the vent-side particulate adsorbent volume iselongated, with a length to diameter ratio, L/D, of greater than 2.

In certain embodiments, the M/m for the at least one vent-sideparticulate adsorbent volume is greater than 150% with flow restrictionproperties of less than 40 Pa/cm pressure drop under 46 cm/s apparentlinear air flow velocity. In certain embodiments, the M/m for thevent-side particulate adsorbent volume is greater than 200% and hasbutane retentivity less than 1 g/dL. In certain embodiments, the M/m forthe vent-side particulate adsorbent volume is greater than 150% and thebutane retentivity is less than 0.5 g/dL.

In certain embodiments, the evaporative emission control canister systemcomprises at least one vent-side particulate adsorbent volume asdescribed herein, e.g., having relatively low butane retentivity and lowflow restriction, wherein the canister system has a two-day DBLemissions of no more than about 50, 45, 40, 35, 30, 25, 20 mg or less atno more than about 175, 150, 125, 120, 115, 110, 100 or less bed volumesof purge or less than 315, 300, 275, 250, 225, 200, 175, 150 or lessliters of purge as determined by the California Bleed Emissions TestProcedure (BETP). In certain embodiments, the evaporative emissioncontrol canister system comprises at least one adsorbent volume havinglow butane retentivity and low flow restriction particulate adsorbentand has no more than 50 mg, or no more than 20 mg day 2 DBL emissionsunder less than 100 bed volumes or less than 210 liters of purge in theBETP test.

In some embodiments, the system comprises a plurality of vent-sideparticulate adsorbent volumes that are configured to permit sequentialcontact by a fluid, e.g., a fuel vapor. In certain embodiments, forexample, the adsorbents are connected in series defining a fluid flowpath therethrough.

In certain embodiments, the system comprises a plurality of canistersthat are connected to permit sequential contact by a fluid, e.g., a fuelvapor.

In other embodiments, the system further comprises a subsequentadsorbent volume that is downstream from or subsequent to the vent-sideparticulate adsorbent volume as described herein (i.e., the subsequentadsorbent volume comes into contact with the fuel vapor after itencounters the vent-side particulate adsorbent volume when the engine isat rest).

In certain embodiments, the at least one subsequent adsorbent volume hasat least one of: i) a BWC of less than about 8 g/dL, ii) an IAC of lessthan about 35 grams n-butane/L between vapor concentrations of 5 vol %and 50 vol % n-butane, or iii) a combination thereof. In certainembodiments, the subsequent adsorbent volume is an activated honeycomb.

In another aspect, the description provides an evaporative emissioncontrol canister system including one or more canisters comprising: atleast one fuel-side adsorbent volume comprising a particulate adsorbenthaving microscopic pores with a diameter of less than about 100 nm,macroscopic pores having a diameter of about 100-100,000 nm, a ratio ofa volume of the macroscopic pores to a volume of the microscopic poresthat is greater than about 150%, and a retentivity of less than about1.0 g/dL; and at least one vent-side particulate adsorbent volumecomprising a particulate adsorbent having microscopic pores with adiameter of less than about 100 nm, macroscopic pores having a diameterof about 100-100,000 nm, a ratio of a volume of the macroscopic pores toa volume of the microscopic pores that is greater than about 150%,wherein the at least one vent-side particulate adsorbent volume has abutane retentivity of less than 1.0 g/dL. In certain embodiments, thevent-side particulate adsorbent volume has a flow restriction propertyof less than 40 Pa/cm when a 46 cm/s apparent linear air flow velocityis applied to a 43 mm diameter bed of the vent-side particulateadsorbent volume. In additional embodiments, the at least one vent-sideparticulate adsorbent volume has a flow restriction of less than 0.3 kPaunder 40 lpm air flow. In further embodiments, the vent-side particulateadsorbent volume has a length to diameter ratio of 2 or greater. Inadditional embodiments, the at least one fuel-side adsorbent volume hasa nominal BWC of greater than 8 g/dL, a nominal IAC at 25 C of more than35 g/L between vapor concentrations of 5 vol % and 50 vol % n-butane, orboth. In certain embodiments, the evaporative emission control canistersystem further comprises at least one vent-side subsequent adsorbentvolume, wherein the at least one vent-side subsequent adsorbent volumehas a nominal BWC of less than 8 g/dL, a nominal IAC at 25 C of lessthan 35 g/L between vapor concentrations of 5 vol % and 50 vol %n-butane, or both. In certain embodiments, the at least one fuel-sideadsorbent volume, the at least one vent-side particulate volume or bothhas a ratio of a volume of the macroscopic pores to a volume of themicroscopic pores that is greater than about 200%, wherein the at leastone vent-side particulate adsorbent volume has a butane retentivity ofless than 1.0 g/dL.

In any of the aspects or embodiments described herein, the systemfurther comprises at least one of: a fuel vapor inlet conduit thatconnects the evaporative emission control canister system to a fueltank; a fuel vapor purge conduit that connects the evaporative emissioncontrol canister system to an air induction system of the engine; a ventconduit for venting the evaporative emission control canister system andfor admission of purge air to the evaporative emission control canistersystem; or a combination thereof.

In some embodiments, the system has at least one of: a fuel vapor flowpath from the fuel vapor inlet conduit through each of the plurality ofadsorbent volumes (i.e., at least one fuel-side adsorbent volumeupstream of at least one vent-side particulate adsorbent volumeupstream, and optionally at least one subsequent adsorbent volume) tothe vent conduit; an air flow path from the vent conduit through each ofthe plurality of adsorbent volumes (i.e., the optional at least onesubsequent adsorbent volume, the at least one vent-side particularadsorbent volume, and the at least one fuel-side adsorbent volume) tothe fuel vapor purge outlet; or both.

In yet another embodiment, a packed bed of the at least one vent-sideparticulate adsorbent volume has a pressure drop that is ≤40 Pa/cm at 46cm/s apparent linear air flow velocity.

In another aspect, the present disclosure provides an evaporativeemission control system comprising: a fuel tank for storing fuel; anengine having an air induction system and adapted to consume the fuel;an evaporative emission control canister system; a fuel vapor purgeconduit connecting the evaporative emission control canister system tothe air induction system of the engine; and a vent conduit for ventingthe evaporative emission control canister system and for admission ofpurge air to the evaporative emission control canister system, whereinthe evaporative emission control canister system is defined by: a fuelvapor inlet conduit connecting the evaporative emission control canistersystem to the fuel tank, a fuel vapor flow path from the fuel vaporinlet conduit through a plurality of adsorbent volumes to the ventconduit, and an air flow path from the vent conduit through theplurality of adsorbent volumes and the fuel vapor purge outlet.

In certain embodiments, the evaporative emission control systemcomprises one or more canisters comprising a plurality of adsorbentvolumes including at least one vent-side particulate adsorbent volumecomprising a particulate adsorbent volume, e.g., a low retentivityparticulate adsorbent having at least one of (i) microscopic pores witha diameter of less than about 100 nm, macroscopic pores having adiameter of about 100-100,000 nm, a ratio of a volume of the macroscopicpores to a volume of the microscopic pores (M/m) that is greater thanabout 150%, (ii) a retentivity of from about 1-0.25 g/dL or less, (iii)a particle diameter of from about 210 mm or (iv) a combination thereof.In certain embodiments, the particle diameter is from about 3-10 mm,from about 3-9 mm, from about 3-8 mm, from about 3-7 mm, from about 3-6mm, from about 3-5 mm, from about 2-9 mm, from about 2-8 mm, from about2-7 mm, or from about 2-6 mm.

In certain embodiments, the at least one vent-side particulate adsorbentvolume has a length/diameter (L/D) ratio of at least 0.5, 1, 1.5, 2 ormore.

In other embodiments, the evaporative emission control system comprisesa plurality of canisters that are connected to permit sequential contactby fuel vapor.

In a further aspect, the present disclosure provides a method forreducing fuel vapor emissions in an evaporative emission control system,the method comprising contacting the fuel vapor with at least onevent-side particulate adsorbent comprising at least one of microscopicpores with a diameter of less than about 100 nm; macroscopic poreshaving a diameter of about 100-100,000 nm; and a ratio of a volume ofthe macroscopic pores to a volume of the microscopic pores (M/m) that isgreater than about 150%, a retentivity of from about 1-0.25 g/dL orless, a particle diameter of from 3-6 mm or a combination thereof.

In some embodiments, the method further comprises contacting the fuelvapor with at least one fuel-side adsorbent volume as described hereinprior to contacting the at least one vent-side particulate adsorbent asdescribed herein.

In any of the aspects or embodiments described herein, the adsorbentsare located within a single canister. In particular embodiments, theadsorbents are located within a plurality of canisters that areconnected to permit sequential contact by the fuel vapor.

The preceding general areas of utility are given by way of example onlyand are not intended to be limiting on the scope of the presentdisclosure and appended claims. Additional objects and advantagesassociated with the compositions, methods, and processes of the presentdisclosure will be appreciated by one of ordinary skill in the art inlight of the instant claims, description, and examples. For example, thevarious aspects and embodiments of the present disclosure may beutilized in numerous combinations, all of which are expresslycontemplated by the present disclosure. These additional advantagesobjects and embodiments are expressly included within the scope of thepresent disclosure. The publications and other materials used herein toilluminate the background of the invention, and in particular cases, toprovide additional details respecting the practice, are incorporated byreference.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated into and form a partof the specification, illustrate several embodiments of the presentinvention and, together with the description, serve to explain theprinciples of the invention. The drawings are only for the purpose ofillustrating an embodiment of the invention and are not to be construedas limiting the invention. Further objects, features and advantages ofthe invention will become apparent from the following detaileddescription taken in conjunction with the accompanying figures showingillustrative embodiments of the invention, in which:

FIG. 1 illustrates a cross-sectional view of an evaporative emissioncontrol canister system according to the present disclosure.

FIG. 2 illustrates a cross-sectional view of an evaporative emissioncontrol canister system according to the present disclosure.

FIGS. 3A, 3B, 3C, 3D, 3E, 3F, 3G, 3H1, 3H2, and 3I illustrate examplesof alternative adsorbent morphologies of the low retentivity particulateadsorbent.

FIG. 4 is a cross-sectional view of an apparatus for measuring pressuredrop produced by the particulate adsorbent.

FIGS. 5, 6, 7, 8, 9, 10, 11, and 12 help to illustrate how NominalVolume Apparent Density is calculated.

FIG. 13 is a simplified schematic drawing of the apparatus used for thedetermination of the butane adsorption capacity.

FIG. 14 shows Table 1. Main canister configuration, including in certainembodiments, main canisters comprising multiple chambers and/or multipleadsorbent volumes.

FIG. 15 shows Table 2-A, Table 2-B, and Table 2-C. Supplemental canisterconfiguration.

FIG. 16 shows Table 3-A, Table 3-B, and Table 3-C, which providessupplemental canister vent-side subsequent adsorbent volume informationfor Examples 29-33, 73, 74, 94, 96, and 106-111.

FIG. 17 is a graph of the Day 2 emissions for Examples 29-31 relative tosystem purge BV.

FIG. 18 is a graph of the adsorbent incremental adsorption capacity vs.vapor path length.

FIG. 19 is a graph of the adsorbent butane working capacity vs. vaporpath length.

FIG. 20 is a graph of the adsorbent g-Total butane working capacity vs.vapor path length.

FIG. 21 illustrates the well-known performance tradeoff withconventional solid particulate adsorbents (cylindrically shaped pellets)with diameters of 2-5 mm in providing the target flexibility ofreasonable flow restriction and DBL emissions performance. Theseexamples are for main canisters with one or more vent-side adsorbentvolumes with alternative adsorbent fills, as described in Tables 2 and3.

FIG. 22 illustrates the effects of the length/diameter ratio on two-dayDBL for an evaporative emission control system having a canister withone or more vent-side adsorbent volumes with alternative adsorbentfills, as described in Tables 2 and 3.

FIG. 23 illustrates the effects of the length/diameter ratio on pressuredrop for an evaporative emission control system having a canister withone or more vent-side adsorbent volumes with alternative adsorbentfills, as described in Tables 2 and 3. Note that the particulateadsorbents as described herein provide reduced bed pressure drop ascompared to currently available particulate adsorbents.

FIG. 24 illustrates the flow restriction of conventional particulateadsorbents and carbon honeycombs for typical flow rates (slpm or lpm).

FIG. 25 shows those typical flow rates in terms of the gas velocitiesfor the vent-side volumes in FIGS. 21 through 23.

FIG. 26 shows inventive examples of particulate adsorbent capable ofproviding for low DBL emissions and low flow restriction performance ascompared to the conventional materials exemplified in FIG. 21.

FIG. 27 illustrates high performing exemplary or inventive vent-sideparticulate adsorbent volumes compared with carbon honeycombs with highchamber L/D of greater than 2.

FIG. 28 illustrates the flow restriction of exemplary or inventiveparticulate adsorbents and carbon honeycombs for typical flow rates(slpm).

FIG. 29 illustrates the effects of the length/diameter ratio on pressuredrop for an evaporative emission control system having one or moreexemplified or inventive vent-side particulate adsorbent volumescompared with carbon honeycombs.

FIG. 30 shows flow rates in terms of the gas velocities for emissioncanister systems including the exemplary or inventive vent-sideparticulate adsorbent volumes compared with carbon honeycombs.

FIG. 31 shows the examples from FIG. 26 where <100 BV and <210 literlevel of purge was applied after the 40 g/hr butane loading step.

FIG. 32 shows that when a second chamber is added, which comprisesinventive examples in a bed (“Adsorbent 2”), the system emissions showslow flow restriction and low emissions.

FIG. 33 shows two-day DBL emissions under low purge conditions (i.e.,<100 BV) for the vent-side particulate adsorbent volumes as describedherein contained in Adsorbent 2 chamber with L/D proportions similar tothose of the carbon honeycombs, with a shift to a lower L/D value.

FIG. 34 shows bed pressure drop for the exemplary or inventive vent-sideparticulate adsorbent volumes of FIGS. 32 and 33 contained in Adsorbent2 chamber with L/D proportions similar to those of the carbonhoneycombs.

FIG. 35 shows two-day DBL emissions under 315 L (139 BV) purgeconditions for the inventive particulates having M/m ratio of ≥150%.

FIG. 36 shows two-day DBL emissions under 315 L (139 BV) purgeconditions for the inventive particulates having retentivity of lessthan about 0.5 g/dL.

FIG. 37 shows two-day DBL emissions under 315 L (137-147 BV) purgeconditions for the inventive particulates having M/m ratio of ≥150%.

FIG. 38 shows two-day DBL emissions under 315 L (137-147 BV) purgeconditions for the inventive particulates having retentivity of lessthan about 0.5 g/dL.

FIG. 39 shows the low flow restriction properties for an exemplaryvent-side low flow restriction particulate in an emission canistersystem compared with carbon honeycombs and conventional particulate.

FIG. 40 shows the low flow restriction properties for an exemplaryvent-side low flow restriction particulate in an emission canistersystem compared with carbon honeycombs and conventional particulate.

FIG. 41 illustrates high performing exemplary vent-side particulateadsorbent volume with high chamber L/D of greater than 2 compared withcarbon honeycombs and conventional particulate.

FIG. 42 shows the pellet strength of the particulate adsorbent in theexamples of FIGS. 26 and 27 as a function of the M/m properties, where“LFR” indicates low flow restriction.

FIG. 43 shows the low flow restriction particulate adsorbents of theexamples of FIGS. 26 and 27, which are able to achieve excellent controlof DBL emissions while demonstrating good pellet strength, and with (ordespite) their high M/m properties.

FIG. 44 illustrates the pellet strengths for exemplary low flowrestriction particulate adsorbents in the examples of FIGS. 35 and 36.

DETAILED DESCRIPTION

The present disclosure will now be described more fully hereinafter, butnot all embodiments of the disclosure are shown. While the disclosurehas been described with reference to exemplary embodiments, it will beunderstood by those skilled in the art that various changes may be madeand equivalents may be substituted for elements thereof withoutdeparting from the scope of the disclosure. In addition, manymodifications may be made to adapt a particular structure or material tothe teachings of the disclosure without departing from the essentialscope thereof.

The drawings accompanying the application are for illustrative purposesonly. They are not intended to limit the embodiments of the presentdisclosure. Additionally, the drawings are not drawn to scale. Elementscommon between figures may retain the same numerical designation.

Where a range of values is provided, it is understood that eachintervening value between the upper and lower limit of that range andany other stated or intervening value in that stated range isencompassed within the invention. The upper and lower limits of thesesmaller ranges may independently be included in the smaller ranges isalso encompassed within the invention, subject to any specificallyexcluded limit in the stated range. Where the stated range includes oneor both of the limits, ranges excluding either both of those includedlimits are also included in the present disclosure.

The following terms are used to describe the present invention. Ininstances where a term is not specifically defined herein, that term isgiven an art-recognized meaning by those of ordinary skill applying thatterm in context to its use in describing the present invention.

The articles “a” and “an” as used herein and in the appended claims areused herein to refer to one or to more than one (i.e., to at least one)of the grammatical object of the article unless the context clearlyindicates otherwise. By way of example, “an element” means one elementor more than one element.

The phrase “and/or,” as used herein in the specification and in theclaims, should be understood to mean “either or both” of the elements soconjoined, i.e., elements that are conjunctively present in some casesand disjunctively present in other cases. Multiple elements listed with“and/or” should be construed in the same fashion, i.e., “one or more” ofthe elements so conjoined. Other elements may optionally be presentother than the elements specifically identified by the “and/or” clause,whether related or unrelated to those elements specifically identified.Thus, as a non-limiting example, a reference to “A and/or B”, when usedin conjunction with open-ended language such as “comprising” can refer,in one embodiment, to A only (optionally including elements other thanB); in another embodiment, to B only (optionally including elementsother than A); in yet another embodiment, to both A and B (optionallyincluding other elements); etc.

As used herein in the specification and in the claims, “or” should beunderstood to have the same meaning as “and/or” as defined above. Forexample, when separating items in a list, “or” or “and/or” shall beinterpreted as being inclusive, i.e., the inclusion of at least one, butalso including more than one, of a number or list of elements, and,optionally, additional unlisted items. Only terms clearly indicated tothe contrary, such as “only one of” or “exactly one of,” or, when usedin the claims, “consisting of,” will refer to the inclusion of exactlyone element of a number or list of elements. In general, the term “or”as used herein shall only be interpreted as indicating exclusivealternatives (i.e., “one or the other but not both”) when preceded byterms of exclusivity, such as “either,” “one of,” “only one of,” or“exactly one of.”

In the claims, as well as in the specification above, all transitionalphrases such as “comprising,” “including,” “carrying,” “having,”“containing,” “involving,” “holding,” “composed of,” and the like are tobe understood to be open-ended, i.e., to mean including but not limitedto. Only the transitional phrases “consisting of” and “consistingessentially of” shall be closed or semi-closed transitional phrases,respectively, as set forth in the 10 United States Patent Office Manualof Patent Examining Procedures, Section 2111.03.

As used herein in the specification and in the claims, the phrase “atleast one,” in reference to a list of one or more elements, should beunderstood to mean at least one element selected from anyone or more ofthe elements in the list of elements, but not necessarily including atleast one of each and every element specifically listed within the listof elements and not excluding any combinations of elements in the listof elements. This definition also allows that elements may optionally bepresent other than the elements specifically identified within the listof elements to which the phrase “at least one” refers, whether relatedor unrelated to those elements specifically identified. Thus, as anonlimiting example, “at least one of A and B” (or, equivalently, “atleast one of A or B,” or, equivalently “at least one of A and/or B”) canrefer, in one embodiment, to at least one, optionally including morethan one, A, with no B present (and optionally including elements otherthan B); in another embodiment, to at least one, optionally includingmore than one, B, with no A present (and optionally including elementsother than A); in yet another embodiment, to at least one, optionallyincluding more than one, A, and at least one, optionally including morethan one, B (and optionally including other elements); etc. It shouldalso be understood that, unless clearly indicated to the contrary, inany methods claimed herein that include more than one step or act, theorder of the steps or acts of the method is not necessarily limited tothe order in which the steps or acts of the method are recited.

As used herein, the terms “gaseous” and “vaporous” are used in a generalsense and, unless the context indicates otherwise, are intended to beinterchangeable.

The term “adsorbent component” or “adsorbent volume,” as used herein,refers to an adsorbent material or adsorbent containing material alongvapor flow path, and may consist of a bed of particulate material, amonolith, honeycomb, sheet or other material.

As described herein, the term “upstream” refers to a location/volumewithin the system that comes into contact with a fluid, e.g. fuel vapor,prior to or before another location/volume of the system. That is, anupstream location/volume is located toward the fuel vapor inlet relativeto a location/volume.

As described herein, the term “downstream” refers to a location/volumewithin the system that comes into contact with a fluid, e.g. fuel vapor,after or subsequent to another location/volume of the system. That is, adownstream location/volume is located distal to the fuel vapor inletrelative to a location/volume.

The description provides an evaporative emission control canistersystems including one or more canisters comprising at least oneparticulate adsorbent volume as described herein. The canisters canfurther comprise additional adsorbent volumes as described herein, e.g.,at least one fuel-side adsorbent volume, and/or at least one vent-sidesubsequent adsorbent volume. In a preferred embodiment, the at least oneparticulate adsorbent volume is located downstream in the fluid pathfrom the fuel-side adsorbent volume (i.e., vent-side particulateadsorbent volume). In additional embodiments, the vent-side particulateadsorbent volume is a low retentivity vent-side particulate adsorbentvolume. As used herein, unless the context indicates otherwise, “lowretentivity” or “low butane retentivity” refers to a butane retentivityof less than about 2 g/dL, and preferably less than about 1 g/dL.

Evaporative Emission Canister Systems

FIG. 1 illustrates a non-limiting example of some embodiments of theevaporative emission control canister system as described hereincomprising a single canister having at least one adsorbent volume, suchas a fuel-side adsorbent volume and at least one vent-side adsorbentvolume (i.e., downstream from the initial adsorbent). Canister system100 includes a support screen 102, a dividing wall 103, a fuel vaporinlet 104 from a fuel tank, a vent port 105 opening to an atmosphere, apurge outlet 106 to an engine, an fuel-side adsorbent volume 201, and atleast one vent-side adsorbent volume 202, 203, 204. It should be noted,however, that any particular adsorbent volume could include one or moreof 201, 202, 203, and 204. That is, a fuel-side adsorbent volume couldinclude 201 and 202, and/or a vent-side adsorbent volume could include203 and 204. The adsorbent volumes are connected (in fluidcommunication) to permit directional and sequential contact by a fluid(e.g., air, gas or fuel vapor).

When an engine is off, the fuel vapor from a fuel tank enters thecanister system 100 through the fuel vapor inlet 104. In this example,the fuel vapor diffuses into the initial fuel-side adsorbent volume 201,and then the at least one vent-side (i.e., downstream) adsorbent volumebefore being released to the atmosphere through the vent port 105 of thecanister system. Once the engine is turned on, ambient air is drawn intothe canister system 100 through the vent port 105. The purge air flowsthrough the at least one vent-side (i.e., downstream) adsorbent volume204, 203, 202 and then the fuel-side adsorbent volume 201, and desorbsthe fuel vapor adsorbed on the adsorbent volumes 204, 203, 202, 201before entering an internal combustion engine through the purge outlet106.

The evaporative emission control canister system may include an emptyvolume within the canister. As used herein, the term “empty volume”refers to a volume not including any adsorbent. Such volume may compriseany non-adsorbent including, but not limited to, air gap, foam spacer,screen, or combinations thereof. The empty volume can be located in anyof the depicted volumes 201, 202, 203, 204 shown in FIG. 1 or found inbetween, before, or after any of the depicted volumes 201, 202, 203,204.

FIG. 2 shows a non-limiting example of further embodiments of theevaporative emission control canister system that includes more than onecanister comprising a plurality of adsorbent volumes. For example, afuel-side adsorbent volume and at least one vent-side adsorbent volumeare located in separate canisters, wherein the adsorbent volumes areconnected (in fluid communication) to permit directional and sequentialcontact by fuel vapor from one volume (and canister) to the next. Asillustrated in FIG. 2, the canister system 100 includes a main canister101, a support screen 102, a dividing wall 103, a fuel vapor inlet 104from a fuel tank, a vent port 105 opening to an atmosphere, a purgeoutlet 106 to an engine, an initial fuel-side adsorbent volume 201 inthe main canister 101, vent-side adsorbent volumes 202, 203, 204downstream from the initial fuel-side adsorbent volume 201 in the maincanister 101, a supplemental canister 300 that includes at least oneadditional vent-side adsorbent volume 301, 302, 303, 304, 305, and aconduit 107 connecting the main canister 101 to the supplementalcanister 300. Similar to that of the main canister, the additionalvent-side adsorbent volume in the supplemental canister can comprise asingle adsorbent located at multiple of the depicted volumes 301, 302,303, 304, 305.

Furthermore, the supplemental canister of the evaporative emissioncontrol canister system may include an empty volume can be found at anyof the depicted volumes 301, 302, 303, 304, 305 shown in FIG. 2 or foundin between, before, or after any of the depicted volumes 301, 302, 303,304, 305. For example, at least one of 302, 304, or both are emptyvolumes. As previously discussed, the term “empty volume” refers to avolume not including any adsorbent. Such volume may comprise anynon-adsorbent including, but not limited to, air gap, foam spacer,screen, conduit, or combinations thereof.

When the engine is off, the fuel vapor from a fuel tank enters thecanister system 100 through the fuel vapor inlet 104 into the maincanister 101. The fuel vapor diffuses through the initial fuel-sideadsorbent volume 201 and then the vent-side adsorbent volumes (202, 203,and 204) in the main canister 101 before entering the supplementalcanister 300 via the conduit 107. The fuel vapor diffuses through thevent-side adsorbent volume or volumes 301, 302, 303, 304, 305 inside thesupplemental canister 300 before being released to the atmospherethrough the vent port 105 of the canister system. Once the engine isturned on, ambient air is drawn into the canister system 100 through thevent port 105. The purge air flows through the vent-side adsorbentvolume or volumes 305, 304, 303, 302, 301 in the supplemental canister300, the vent-side adsorbent volumes (204, 203, 202) in the maincanister 101, and then the fuel-side adsorbent volume 201 in the maincanister 101, to desorb the fuel vapor adsorbed on the adsorbent volumes(305, 304, 303, 302, 301, 204, 203, 202, 201) before entering theinternal combustion engine through the purge outlet 106.

Furthermore, the evaporative emission control canister system mayinclude an empty volume between the main canister and the supplementalcanister.

When desired, the evaporative emission control canister system mayinclude more than one supplemental canister, as describe herein. Theevaporative emission control canister system may further include one ormore empty volumes between the main canister and a first supplementalcanister, between the supplement canisters, and/or at the end of thelast supplemental canister. By way of non-limiting example, theevaporative emission control canister system may include a maincanister, a first supplemental canister, a second supplemental canister,a third supplemental canister, an empty volume between the main canisterand a first supplemental canister, an empty volume between the first andsecond supplemental canister, and an empty volume at the end of thethird supplemental canister. Each of the supplemental canisters canfurther include one or more additional adsorbent volumes.

When desired, the total adsorbent volume (i.e., the sum of the adsorbentvolumes) may be the same as the volume of the evaporative emissioncontrol canister system. Alternatively, the total adsorbent volume maybe less than the volume of the evaporative emission control canistersystem.

Thus, one aspect, the disclosure provides an evaporative emissioncontrol canister system comprising one or more canisters having aplurality of chambers, each defining a volume, which are connected or influid communication permitting a fluid (e.g., air, gas or fuel vapor) toflow directionally and sequentially from one chamber to the next,wherein at least one chamber comprises at least one particulateadsorbent volume that includes a particulate adsorbent havingmicroscopic pores with a diameter of less than about 100 nm, macroscopicpores having a diameter of about 100-100,000 nm, and a ratio of a volumeof the macroscopic pores to a volume of the microscopic pores that isgreater than about 150%, and wherein the at least one particulateadsorbent volume has at least one of: (i) a flow restriction property ofless than 40 Pa/cm pressure drop under conditions of 46 cm/s apparentlinear air flow velocity applied to a 43 mm diameter bed of theparticulate adsorbent material, (ii) a flow restriction of less than 0.3kPa under 40 lpm air flow, (iii) a butane retentivity of less than about0.5 g/dL, (iv) a length to diameter (L/D) ratio of greater than about 2or (v) a combination thereof.

In certain embodiments, canister system comprises at least oneadditional adsorbent volume. In certain embodiments, the adsorbentvolumes are located within a single canister or within a plurality ofcanisters that are connected to permit sequential contact by the fuelvapor.

In certain embodiments, the canister system further comprises at leastone fuel-side adsorbent volume, wherein the at least one fuel-sideadsorbent volume has a nominal BWC of >8 g/dL, a nominal IAC at 25° C.of >35 g/L between vapor concentrations of 5 vol % and 50 vol %n-butane, or both.

In certain embodiments, the canister system further comprises at leastone vent-side subsequent adsorbent volume, wherein the at least onevent-side subsequent adsorbent volume has a nominal BWC of less than 8g/dL, a nominal IAC at 25° C. of less than 35 g/L between vaporconcentrations of 5 vol % and 50 vol % n-butane, or both. In certainembodiments, the at least one particulate adsorbent volume, the at leastone vent-side subsequent adsorbent volume or both have a BWC of lessthan 8 g/dL, an IAC at 25° C. of less than 35 g/L between vaporconcentrations of 5 vol % and 50 vol % n-butane.

In certain embodiments, the evaporative emission control canister systemcomprises at least one fuel-side adsorbent volume having a nominalbutane working capacity (BWC) of at least 8 g/dL (e.g., at least 10g/L), a nominal incremental adsorption capacity (IAC) at 25° C. of atleast 35 g/L between vapor concentrations of 5 vol % and 50 vol %n-butane, or both.

In certain embodiments, the adsorbent volumes are located within asingle canister or within a plurality of canisters that are connected topermit sequential contact by the fuel vapor.

In certain embodiments, the particulate adsorbent volume has an M/mratio that is greater than about 200%. In certain embodiments, theparticulate adsorbent volume has a butane retentivity of less than about2.0 g/dL or less than 1.0 g/dL or less than 0.5 g/dL.

In certain embodiments, the at least one particulate adsorbent islocated on the vent-side of the canister system, the fuel-side of thecanister system or both.

In certain embodiments, the evaporative emission control canister systemcomprises at least one fuel-side adsorbent volume, at least onevent-side subsequent adsorbent volume or both.

In certain embodiments, the adsorbent volumes are located within asingle canister or within a plurality of canisters that are connected topermit sequential contact by the fuel vapor. In certain embodiments, theat least one particulate adsorbent volume, the at least one fuel-sideadsorbent volume or both have a BWC of at least 8 g/dL (e.g., at least10 g/L), an IAC at 25° C. of at least 35 g/L between vaporconcentrations of 5 vol % and 50 vol % n-butane, or both. In certainembodiments, the at least one particulate adsorbent volume, the at leastone vent-side subsequent adsorbent volume or both have a BWC of lessthan 8 g/dL, an IAC at 25° C. of less than 35 g/L between vaporconcentrations of 5 vol % and 50 vol % n-butane, or both. In certainembodiments, the particulate volume has a ratio of a volume of themacroscopic pores to a volume of the microscopic pores that is greaterthan about 200%.

In another aspect, the description provides an evaporative emissioncontrol canister system including one or more canisters comprising atleast one fuel-side adsorbent volume (i.e., adsorbent volume at or nearthe fuel tank vapor inlet 104), and at least one vent-side particulateadsorbent volume, e.g., a vent-side low retentivity particulateadsorbent volume. The term “vent-side” refers to a position that isdownstream or closer to the vent port relative to the at least onefuel-side adsorbent volume. As such, while the vehicle is at rest, theat least one fuel-side adsorbent volume comes into contact with the fuelvapor from the gas tank prior to any other adsorbent volumes which arelocated downstream from the fuel-side adsorbent volume in the fluid pathfrom fuel tank to vent port (i.e., downstream directionally from 104 to105).

In some embodiments, the system comprises a plurality of vent-sideparticulate adsorbent volumes, e.g., vent-side low retentivityparticulate adsorbent volumes, that are configured to permit sequentialcontact by a fluid, e.g., a fuel vapor. In certain embodiments, forexample, the adsorbents are connected in series defining a fluid flowpath therethrough. In certain embodiments, the system comprises aplurality of canisters that are connected to permit sequential contactby a fluid, e.g., a fuel vapor.

With reference to FIGS. 1 and 2, the adsorbents can be located within asingle canister or within multiple canisters connected to permitsequential contact by a fluid, e.g. fuel vapor (e.g., 2, 3, 4, 5, 6, 7,or 8 canisters). In a particular embodiment, the adsorbents are locatedwithin a plurality of canisters that are connected to permit sequentialcontact by the fuel vapor. For example, in certain embodiments, thevent-side particulate adsorbent volume e.g., a vent-side low retentivityparticulate adsorbent volume, is in at least one volume of the maincanister, e.g., with reference to FIGS. 1 and 2, 202, 203, or 201;and/or at least one volume of a supplemental canister, e.g., 301, 302,303, 304, or 305. As such, in certain embodiments, the low retentivityparticulate adsorbent can be found in at least one volume of the maincanister 201, 202, 203, and 204; at least on volume of a supplementalcanister 301, 302, 303, 304, 305, or a combination thereof.

The disclosure also contemplates including additional adsorbent volumesin any number of combinations that would be readily understood from thedisclosure. For example, an additional vent-side or low retentivityparticulate adsorbent as described herein could be present after ordownstream of a vent-side subsequent adsorbent volume. If a supplementalcanister is present, the supplemental canister may comprise a vent-sideor low retentivity adsorbent volume at the vent port side (e.g., volume305) and the main canister side (e.g., volume 301) with downstreamvent-side subsequent adsorbent volume(s) located therebetween (e.g.,volumes 302, 303, 304). Similarly, a vent-side or low retentivityadsorbent can be present on the main canister side of the supplementalcanister (e.g., volume 301) and the supplemental canister side of themain canister (e.g., volume 204), wherein the canister system compriseshigh butane working capacity adsorbent upstream from the vent-side orlow retentivity adsorbent. The system could also be configured toinclude a vent-side subsequent adsorbent volume (e.g., volume 304)downstream from the vent-side or low retentivity adsorbent volume (e.g.,volume 301), which could optionally include a further low retentivityadsorbent volume after the subsequent adsorbent volume (e.g., volume305).

In any of the aspects or embodiments described herein, the the vent-sideparticulate adsorbent has microscopic pores with a diameter of less thanabout 100 nm, macroscopic pores having a diameter of about 100-100,000nm and a ratio of a volume of the macroscopic pores to a volume of themicroscopic pores (M/m) that is greater than about 150%, 160%, 170%,180%, 190%, 200%, 210%, 220%, 250%, 275%, 280%, 300% or more. In certainembodiments, the vent-side particulate adsorbent has an M/m ratio offrom 150% to about 170%, from about 160% to about 180%, from about 170%to about 190%, from about 180% to about 200%, from 190% to about 210%,from 200% to about 220%, or greater than 220%. In other embodiments, theratio of volumes is greater than about 150% to about 1000%, greater thanabout 150% to about 800%, greater than about 150% to about 600%, greaterthan about 150% to about 500%, greater than about 150% to about 400%,greater than about 150% to about 300%, greater than about 150% to about200%, about 175% to about 1000%, about 175% to about 800%, about 175% toabout 600%, about 175% to about 500%, about 175% to about 400%, about175% to about 300%, about 175% to about 200%, about 200% to about 800%,about 200% to about 600%, about 200% to about 500%, about 200% to about400%, about 200% to about 300%, about 300% to about 800%, about 300% toabout 600%, about 300% to about 500%, about 300% to about 400%, about400% to about 800%, about 400% to about 600%, about 400% to about 500%,about 500% to about 800%, about 500% to about 600%, or about 600% toabout 800%.

In any of the aspects or embodiments described herein, the vent-sideparticulate adsorbent volume, e.g., vent-side low retentivityparticulate adsorbent volume, has a flow restriction of less than about0.3 kPa under 40 lpm air flow, flow restriction properties of less than40 Pa/cm pressure drop under 46 cm/s apparent linear air flow velocityor both.

In any of the aspects or embodiments described herein the vent-sideparticulate adsorbent volume, e.g., vent-side low retentivityparticulate adsorbent volume, has a length to diameter ratio (L/D) ofabout 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5 or greater,including all values in between. In certain embodiments, the vent-sideparticulate adsorbent volume is elongated, with an L/D ratio of greaterthan about 2. In certain embodiments, the L/D ratio is from about 1.0 toabout 6.0, from about 1.25 to about 5.75, from about 1.5 to about 5.5,from about 1.75 to about 5.0, or from about 2 to about 4.75.

In any of the aspects or embodiments described herein, the at least onevent-side particulate adsorbent volume, e.g., vent-side low retentivityparticulate adsorbent volume, has a butane retentivity of ≤about 2 g/dL,≤about 1.5 g/dL, ≤about 1 g/dL, ≤about 0.9 g/dL, ≤about 0.8 g/dL, ≤about0.7 g/dL, ≤about 0.6 g/dL, ≤about 0.5 g/dL, ≤about 0.4 g/dL, ≤about 0.3g/dL, ≤about 0.2 g/dL, or ≤about 0.1 g/dL. In certain embodiments, theat least one vent-side particulate adsorbent volume, e.g., vent-side lowretentivity particulate adsorbent volume, has a butane retentivity offrom about 0.01 g/dL to about 2.5 g/dL, from about 0.01 g/dL to about2.0 g/dL, from about 0.01 g/dL to about 1.5 g/dL, from about 0.01 g/dLto about 1.0 g/dL, from about 0.01 g/dL to about 0.75 g/dL, from about0.25 g/dL to about 1.00 g/dL, from about 0.25 g/dL to about 0.75 g/dL,from about 0.25 g/dL to about 0.50 g/dL, from about 0.50 g/dL to about1.00 g/dL, from about 0.50 g/dL to about 0.75 g/dL, or from about 0.75g/dL to about 1.00 g/dL

An advantageous feature of the particulate adsorbent described herein,e.g., the low retentivity adsorbent as described herein, is that it haslow flow restriction properties, sufficiently so, that it may be used asa replacement for, e.g., a foam, polymer or paper sheet, or a honeycombmonolith adsorbent. For example, FIG. 21 shows how prior art particulateadsorbent of 2-3 mm in diameter has many times the flow restriction of acommercially available carbon honeycomb employed on the vent-side of acanister system as an emissions “scrubber.” Thus, in any of the aspectsor embodiments, the vent-side particulate adsorbent, e.g., vent-side lowretentivity adsorbent has particle diameter that is from about 3-10 mm,from about 3-9 mm, from about 3-8 mm, from about 3-7 mm, from about 3-6mm, from about 3-5 mm, or from about 3-4 mm.

In certain embodiments, the main canister comprises a high butaneworking capacity adsorbent, the vent-side of the main canister and/orthe main canister-side of a supplemental canister comprises lowretentivity particulate adsorbent as described herein, and the ventportion of the supplemental canister comprises a vent-side subsequentadsorbent volume. In certain embodiments, the vent-side subsequentadsorbent volume is a material with low flow restriction, e.g., a foam,polymer or paper sheet, or honeycomb such as an activated carbonhoneycomb.

In certain embodiments, the at least one fuel-side adsorbent volume hasat least one of a high butane working capacity (BWC) relative to thevent-side adsorbent volume, an effective incremental adsorption capacityof greater than about 35 grams n-butane per liter (g/L) between vaporconcentration of 5 vol % and 50 vol % n-butane, or both.

In any of the aspects or embodiments described herein, the canistersystem fuel-side adsorbent volume has at least one of: i) a nominalbutane working capacity (BWC) greater than 8, 9, 10, 11, 12, 13, 14, 15,16, 17, 18, 19, 20, 21, 22, 23, 24, 25 g/dL or more grams per deciliter(g/dL), ii) an incremental adsorbent capacity of greater than 35, 36,37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54,55, 60, 65, 70, 75, 80, 85, 90 or more grams n-butane per liter (g/L)between vapor concentration of 5 vol % and 50 vol % n-butane, or both.

In certain embodiments, the high butane working capacity adsorbentincludes a high working capacity activated carbon. Such are commerciallyavailable as NUCHAR® BAX 1100, NUCHAR® BAX 1100 LD, NUCHAR® BAX 1500,and NUCHAR® BAX 1700 (Ingevity®, North Charleston, S.C., USA). The highbutane working capacity volume could include a plurality of volumescomprising high butane working capacity adsorbent. For example, the maincanister could include two high butane working capacity volumes (e.g., aNUCHAR® BAX 1100 volume and a NUCHAR® BAX 1500 volume).

In any of the aspects or embodiments described herein, the evaporativeemission control canister system further comprises at least onevent-side subsequent adsorbent volume, wherein the at least onevent-side subsequent adsorbent volume has a nominal BWC of less than 8,7, 6, 5, 4, 3, 2, or 1 g/dL, a nominal IAC at 25° C. of less than 35,34, 33, 32, 31, 30, 29, 28, 37, 36, 35, 34 23, 22, 21, 20, 19, 18, 17,16, 15, 14, 13, 12, 11, 10, 9, 8, 77, 6, 5, 4, 3, 2, or 1 g/L betweenvapor concentrations of 5 vol % and 50 vol % n-butane, or both. Incertain embodiments, the at least one vent-side subsequent adsorbentvolumes as a BWC of from about 1 g/dL to about 8 g/dL, from about 1 g/dLto about 7 g/dL, from about 1 g/dL to about 6 g/dL, from about 1 toabout 5 g/dL, from about 1 g/dL to about 4 g/dL, or from about 1 g/dL toabout 3 g/dL. In certain embodiments, the at least one vent-sidesubsequent adsorbent volumes as an IAC (grams n-butane/L) of from about1 g/L to about 35 g/L, from about 2 g/L to about 30 g/L, from about 3g/L to about 25 g/L, from about 3 g/L to about 20 g/L, from about 3 g/Lto about 15 g/L, or from about 3 g/L to about 10 g/L between vaporconcentrations of 5 vol % and 50 vol % n-butane.

In certain embodiments, the at least one vent-side subsequent adsorbentvolume has at least one of: i) a BWC of less than about 8, 7, 6, 5, 4,3, 2, or 1 g/dL, ii) an IAC of less than about 35, 30, 25, 20, 15, 10,or 5 grams n-butane/L between vapor concentrations of 5 vol % and 50 vol% n-butane, or iii) a combination thereof. In certain embodiments, thesubsequent adsorbent volume is an activated carbon honeycomb.

In certain embodiments, the subsequent adsorbent volume is upstream,downstream or both (i.e., a vent-side subsequent adsorbent volume) inthe vapor pathway from the vent-side particulate adsorbent volume asdescribed herein.

In any of the aspects or embodiments described herein, the vent-sidesubsequent/downstream adsorbent/volume is selected from the groupconsisting of a honeycomb adsorbent (e.g., HCA, HCA-LBE, or Square HCAavailable from Ingevity®, North Charleston, S.C., USA), a monolithadsorbent, or both.

The disclosed evaporative emission control systems provide low diurnalbreathing loss (DBL) emissions even under a low purge condition. Incertain embodiments, the evaporative emission performance of thedisclosed evaporative emission control system may be no more than 50 mg,or within the regulation limits defined by the California BleedEmissions Test Procedure (BETP), which is no more than 20. In any aspector embodiment described herein, the evaporative emission canister systemdescribed herein has a two-day DBL of from about 5 to about 50 mg, fromabout 6 to about 50 mg, from about 7 to about 50 mg, from about 8 toabout 50 mg, from about 9 to about 50 mg, from about 10 to about 50 mg,from about 5 to about 45 mg, from about 5 to about 40 mg, from about 5to about 35 mg, from about 5 to about 30 mg, from about 5 to about 20mg, from about 5 to about 15 mg, or from about 5 to about 10 mg at nomore than about 175, 150, 125, 120, 115, 110, 100 or less bed volumes ofpurge, or less than 315, 300, 275, 250, 225, 200, 175, 150 or lessliters of purge as determined by the California Bleed Emissions TestProcedure (BETP).

The evaporative emission control system may provide low diurnalbreathing loss (DBL) emissions even when being purged at or below 210liters applied after the 40 g/hr butane loading step. In someembodiments, the evaporative emission control system may be purged at orbelow 157.5 liters applied after the 40 g/hr butane loading step.

The evaporative emission control system may provide low diurnalbreathing loss (DBL) emissions even when being purged at or below 150 BVapplied after the 40 g/hr butane loading step. The evaporative emissioncontrol system may provide low diurnal breathing loss (DBL) emissionseven when being purged at or below 100 BV applied after the 40 g/hrbutane loading step. In some embodiments, the evaporative emissioncontrol system may be purged at or below 75 BV applied after the 40 g/hrbutane loading step.

In certain embodiments, the evaporative emission control canister systemcomprises at least one vent-side particulate adsorbent volume, e.g., avent-side low retentivity particulate adsorbent volume, wherein the atleast one vent-side particulate adsorbent has an M/m ratio of greaterthan 150%, and at least one of relatively low flow restrictionproperties, butane retentivity of <1.0 g/dL or both. For example, incertain embodiments, the vent-side particulate adsorbent has an M/m ofgreater than 150%, and at least one of at least one of a butaneretentivity of less than about 0.5 g/dL, a flow restriction of less thanless than 40 Pa/cm pressure drop under 46 cm/s apparent linear gas flowvelocity, a flow restriction of less than 0.3 kPa under 40 lpm air flow,a length to diameter ratio (L/D) of greater than 2 or a combinationthereof. In further embodiments, the vent-side particulate adsorbentvolume has an M/m of greater than 200%, and at least one of at least oneof a butane retentivity of less than about 1 g/dL, a flow restriction ofless than less than 40 Pa/cm pressure drop under 46 cm/s apparent lineargas flow velocity, a flow restriction of less than 0.3 kPa under 40 lpmair flow, a length to diameter ratio (L/D) of greater than 2 or acombination thereof.

In certain embodiments, the vent-side particulate adsorbent, e.g.,vent-side low retentivity particulate adsorbent, as described herein hasan M/m of is greater than 150% with flow restriction properties of lessthan 40 Pa/cm pressure drop under 46 cm/s apparent linear air flowvelocity. In certain embodiments, the M/m for the vent-side particulateadsorbent, e.g., vent-side low retentivity particulate adsorbent, isgreater than 200%, and the butane retentivity is less than 1 g/dL. Incertain embodiments, the M/m for the vent-side particulate adsorbent isgreater than 150% and the butane retentivity is less than 0.5 g/dL.

In certain embodiments, the evaporative emission control systemcomprises one or more canisters comprising a plurality of adsorbentvolumes including at least one vent-side particulate adsorbent volumecomprising, e.g., a low retentivity particulate adsorbent having atleast one of (i) microscopic pores with a diameter of less than about100 nm, macroscopic pores having a diameter of about 100-100,000 nm, aratio of a volume of the macroscopic pores to a volume of themicroscopic pores (M/m) that is greater than about 150%, (ii) a butaneretentivity of from about 1 g/dL to about 0.25 g/dL or less, (iii) aparticle diameter of from about 210 mm or (iv) a combination thereof.

In any of the aspects or embodiments described herein, the evaporativeemission control canister system has a two-day DBL emissions of no morethan about 50, 45, 40, 35, 30, 25, 20 mg at no more than about 175, 150,125, 120, 115, 110, 100 or less bed volumes of purge or less than 315,300, 275, 250, 225, 200, 175, 150 or less liters of purge as determinedby the California Bleed Emissions Test Procedure (BETP).

In certain embodiments, the evaporative emission control canister systemcomprises at least one vent-side particulate adsorbent has an M/m>150%,wherein the vent-side particulate adsorbent volume, e.g., vent-side lowretentivity particulate volume, has at least one of a flow restrictionof less than less than 40 Pa/cm pressure drop under 46 cm/s apparentlinear gas flow velocity, or a flow restriction of less than 0.3 kPaunder 40 lpm air flow, and wherein the canister system and has no morethan 50 mg, or no more than 20 mg day 2 DBL emissions under less than100 bed volumes or less than 210 liters of purge in the BETP test.

In a further aspect, the present disclosure provides an evaporativeemission control canister system comprising: one or more canisterscomprising at least one vent-side particulate adsorbent volume havinglow retentivity, the low retentivity particulate adsorbent volumeincluding one or more low retentivity particulate adsorbent materials.In certain embodiments, the low retentivity particulate adsorbentmaterial has microscopic pores with a diameter of less than about 100nm; macroscopic pores having a diameter of about 100-100,000 nm; and aratio of a volume of the macroscopic pores to a volume of themicroscopic pores that is greater than about 200%, wherein theparticulate adsorbent material has a retentivity of about 1.0 g/dL orless.

For example, the system may comprise an upstream adsorbent volumecomprising a high butane working capacity adsorbent that is locatedupstream from or prior to a low retentivity adsorbent volume (i.e., thehigh butane working capacity adsorbent volume comes into contact withthe fluid, e.g. a fuel vapor, before the low retentivity adsorbent). Thehigh butane working capacity adsorbent volume may have an adsorbent withat least one of: a nominal butane working capacity of at least 8 g/dL(e.g., at least 10 g/dL); a nominal incremental adsorption capacity(IAC) of at least 35 g/L (e.g., at least 45 g/L); or a combinationthereof.

The system of the present disclosure may comprise an adsorbent volumethat is located downstream from or subsequent to a low retentivityadsorbent volume (i.e., the upstream adsorbent volume comes into contactwith the fuel vapor after the low retentivity adsorbent volume). Thedownstream adsorbent volume may comprise an adsorbent that has:microscopic pores with a diameter of less than about 100 nm; macroscopicpores having a diameter of about 100-100,000 nm; and a ratio of a volumeof the macroscopic pores to a volume of the microscopic pores that isless than or equal to about 150%. For example, the downstream orsubsequent adsorbent may have a ratio of a volume of the macroscopicpores to a volume of the microscopic pores that is equal to or less thanabout 150%, equal to or less than about 145%, equal to or less thanabout 140%, equal to or less than about 135%, or equal to or less thanabout 130%.

In certain embodiments, the at least one vent-side particulate adsorbentvolume e.g., a vent-side low retentivity particulate adsorbent volume,is included as an alternative to or in combination with one or morevent-side subsequent adsorbent volumes. The at least one fuel-sideadsorbent volume, the at least one vent-side particulate adsorbentvolume, and/or the at least one vent-side subsequent adsorbent volumecan be contained either in a single canister or in separate canistersthat are connected to permit sequential contact by fuel vapor (andconversely, purge air). In certain embodiments, the at least onevent-side subsequent adsorbent volume includes a non-particulateadsorbent material, e.g., a foam, monolith, a polymer or paper sheet, orhoneycomb (e.g., activated carbon honeycomb), wherein the at least onevent-side subsequent adsorbent volume imposes low vapor or fluid flowrestriction.

In certain embodiments, the evaporative emission control canister systemcomprises: at least one vent-side subsequent adsorbent volume e.g., avent-side low retentivity particulate adsorbent volume, that is upstreamof the at least one vent-side particulate adsorbent volume (i.e.,located closer to the fuel-side adsorbent volume or fuel vapor inlet inthe fluid path), at least one vent-side subsequent adsorbent volume thatis downstream of the at least one vent-side particulate adsorbent volume(i.e., located closer to the vent port in the fluid path), or acombination thereof.

In certain embodiments, the evaporative emission control canister systemcomprises: at least one vent-side particulate adsorbent volume, e.g., avent-side low retentivity particulate adsorbent volume, that is upstreamof the at least one vent-side subsequent adsorbent volume (i.e., locatedcloser to the fuel-side adsorbent volume or fuel vapor inlet in thefluid path), at least one vent-side particulate adsorbent volume that isdownstream of the at least one vent-side subsequent adsorbent volume(i.e., located closer to the vent port in the fluid path), or acombination thereof.

In some embodiments, the evaporative emission control system may furtherinclude one or more heat input unit(s) for heating one or more adsorbentvolume(s) and/or one or more empty volume(s). The heat input units mayinclude, but are not limited to, internal resistive elements, externalresistive elements, or heat input units associated with the adsorbent.The heat input unit associated with the adsorbent may be an elementseparate from the adsorbent (i.e., non-contacted with adsorbents).Alternatively, the heat input unit associated with the adsorbent may bea substrate or layer on to which the adsorbent is attached, bonded,non-bonded, or in physical contact. The heat input unit associated withthe adsorbent may be adsorbent directly heated electrically by havingappropriate resistivity. The resistivity properties of the adsorbent maybe modified by the addition of conductive or resistive additives andbinders in the original preparation of the adsorbent and/or in theforming of the adsorbent into particulate or monolithic forms. Theconductive component may be conductive adsorbents, conductivesubstrates, conductive additives and/or conductive binders. Theconductive material may be added in adsorbent preparation, added inintermediate shaping process, and/or added in adsorbent shaping intofinal form. Any mode of heat input unit may be used. By way ofnon-limiting example, the heat input unit may include a heat transferfluid, a heat exchanger, a heat conductive element, and positivetemperature coefficient materials. The heat input unit may or may not beuniform along the heated fluid path length (i.e., provide differentlocal intensities). Furthermore, the heat input unit may or may not bedistributed for greater intensity and duration of heating at differentpoints along the heated fluid path length.

In general, the low retentivity particulate adsorbent comprises: anadsorbent having microscopic pores with a diameter of less than about100 nm; macroscopic pores having a diameter of about 100-100,000 nm; anda ratio of a volume of the macroscopic pores to a volume of themicroscopic pores is greater than about 150%, wherein the particulateadsorbent material has a retentivity of about 1.0 g/dL or less.

Any suitable adsorbent materials may be used in preparing the adsorbentvolumes as described including, but not limited to, activated carbon,carbon charcoal, zeolites, clays, porous polymers, porous alumina,porous silica, molecular sieves, kaolin, titania, ceria, or combinationsthereof. Activated carbon may be derived from various carbon precursors.By way of non-limiting example, the carbon precursors may be wood, wooddust, wood flour, cotton linters, peat, coal, coconut, lignite,carbohydrates, petroleum pitch, petroleum coke, coal tar pitch, fruitpits, fruit stones, nut shells, nut pits, sawdust, palm, vegetables suchas rice hull or straw, synthetic polymer, natural polymer,lignocellulosic material, or combinations thereof. Furthermore,activated carbon may be produced using a variety of processes including,but are not limited to, chemical activation, thermal activation, orcombinations thereof.

The described low retentivity particulate adsorbent may be at least oneof activated carbon (which may be derived from at least one materialselected from the group consisting of wood, wood dust, wood flour,cotton linters, peat, coal, coconut, lignite, carbohydrates, petroleumpitch, petroleum coke, coal tar pitch, fruit pits, fruit stones, nutshells, nut pits, sawdust, palm, vegetables, synthetic polymer, naturalpolymer, lignocellulosic material, and combinations thereof), carboncharcoal, molecular sieves, porous polymers, porous alumina, clay,porous silica, kaolin, zeolites, metal organic frameworks, titania,ceria, or a combination thereof.

A variety of adsorbent forms may be used. Non-limiting examples of theadsorbent forms may include granular, pellet, spherical, honeycomb,monolith, pelletized cylindrical, particulate media of uniform shape,particulate media of non-uniform shape, structured media of extrudedform, structured media of wound form, structured media of folded form,structured media of pleated form, structured media of corrugated form,structured media of poured form, structured media of bonded form,non-wovens, wovens, sheet, paper, foam, or combinations thereof. Theadsorbent (either as a single component or a blend of differentcomponents) may include a volumetric diluent. Non-limiting examples ofthe volumetric diluents may include, but are not limited to, spacer,inert gap, foams, fibers, springs, or combinations thereof. Furthermore,the adsorbents may be extruded into special thin-walled cross-sectionalshapes, such as hollow-cylinder, star, twisted spiral, asterisk,configured ribbons, or other shapes within the technical capabilities ofthe art. In shaping, inorganic and/or organic binders may be used.

The honeycomb adsorbents may be in any geometrical shape including, butare not limited to, round, cylindrical, or square. Furthermore, thecells of honeycomb adsorbents may be of any geometry. Honeycombs ofuniform cross-sectional areas for the flow-through passages, such assquare honeycombs with square cross-sectional cells or spiral woundhoneycombs of corrugated form, may perform better than round honeycombswith square cross-sectional cells in a right angled matrix that providesadjacent passages with a range of cross-sectional areas and thereforepassages that are not equivalently purged. Without being bound by anytheory, it is believed that the more uniform cell cross-sectional areasacross the honeycomb faces, the more uniform flow distribution withinthe part during both adsorption and purge cycles, and, therefore, lowerDBL emissions from the canister system.

The system of the present disclosure may comprise at least one of: afuel vapor inlet conduit that connects the evaporative emission controlcanister system to a fuel tank; a fuel vapor purge conduit that connectsthe evaporative emission control canister system to an air inductionsystem of the engine; a vent conduit for venting the evaporativeemission control canister system and for admission of purge air to theevaporative emission control canister system; or a combination thereof.The system may be have at least one of: a fuel vapor flow path from thefuel vapor inlet conduit through each of the plurality of adsorbentvolumes (i.e., an initial adsorbent volume upstream of at least onesubsequent adsorbent volume, wherein at least one adsorbent volumeincludes low retentivity particulate adsorbent) to the vent conduit; anair flow path from the vent conduit through each of the plurality ofadsorbent volumes (i.e., a subsequent adsorbent volume followed by aninitial adsorbent upstream of the subsequent adsorbent) to the fuelvapor purge outlet; or both.

In another aspect, the present disclosure provides an evaporativeemission control system comprising: a fuel tank for storing fuel; anengine having an air induction system and adapted to consume the fuel;an evaporative emission control canister system; a fuel vapor purgeconduit connecting the evaporative emission control canister system tothe air induction system of the engine; and a vent conduit for ventingthe evaporative emission control canister system and for admission ofpurge air to the evaporative emission control canister system, whereinthe evaporative emission control canister system is defined by: a fuelvapor inlet conduit connecting the evaporative emission control canistersystem to the fuel tank, a fuel vapor flow path from the fuel vaporinlet conduit through a plurality of adsorbent volumes to the ventconduit, and an air flow path from the vent conduit through theplurality of adsorbent volumes and the fuel vapor purge outlet. Theevaporative emission control system comprising: one or more canisterscomprising a plurality of adsorbent volumes including at least one lowretentivity adsorbent volume comprising a low retentivity particulateadsorbent having: microscopic pores with a diameter of less than about100 nm; macroscopic pores having a diameter of about 100-100,000 nm; aratio of a volume of the macroscopic pores to a volume of themicroscopic pores that is greater than about 150%; and a retentivity ofabout 1.0 g/dL or less. The evaporative emission control systemcomprises a plurality of canisters that are connected to permitsequential contact by fuel vapor.

In some embodiments, the evaporative emission control system may includea heat unit to further enhance the purge efficiency. By way ofnon-limiting example, the evaporative emission control system mayinclude a heat unit for heating the purge air, at least one of the lowretentivity adsorbent volume and/or the subsequent adsorbent volume, orboth.

According to an aspect, the present disclosure provides a method forreducing fuel vapor emissions in an evaporative emission controlcanister system, the method comprising contacting the fuel vapor with aparticulate adsorbent volume e.g., a vent-side low retentivityparticulate adsorbent volume, having microscopic pores with a diameterof less than about 100 nm, macroscopic pores having a diameter of about100-100,000 nm, and a ratio of a volume of the macroscopic pores to avolume of the microscopic pores that is greater than about 150%, whereinthe particulate adsorbent material has a flow restriction property ofless than about 40 Pa/cm under conditions of 46 cm/s apparent linear airflow velocity applied to a 43 mm diameter bed of the particulateadsorbent material.

Fuel-Side and Vent-Side

In another aspect, the description provides an evaporative emissioncontrol canister system including one or more canisters comprising: atleast one fuel-side particulate adsorbent volume comprising havingmicroscopic pores with a diameter of less than about 100 nm, macroscopicpores having a diameter of about 100-100,000 nm, a ratio of a volume ofthe macroscopic pores to a volume of the microscopic pores that isgreater than about 150%, and a retentivity of less than about 0.5 g/dLor a ratio of a volume of the macroscopic pores to a volume of themicroscopic pores that is greater than about 200%, and a retentivity ofless than about 1 g/dL; and at least one vent-side particulate adsorbentvolume comprising a particulate adsorbent having microscopic pores witha diameter of less than about 100 nm, macroscopic pores having adiameter of about 100-100,000 nm, a ratio of a volume of the macroscopicpores to a volume of the microscopic pores that is greater than about150%, wherein the at least one vent-side particulate adsorbent volumehas a butane retentivity of less than 0.5 g/dL or a ratio of a volume ofthe macroscopic pores to a volume of the microscopic pores that isgreater than about 200%, and a retentivity of less than about 1 g/dL. Incertain embodiments, the fuel-side particulate adsorbent volume, thevent-side particulate adsorbent volume or both have a flow restrictionproperty of less than 40 Pa/cm when a 46 cm/s apparent linear air flowvelocity is applied to a 43 mm diameter bed of the vent-side particulateadsorbent volume. In additional embodiments, the at least one fuel-sideparticulate adsorbent volume, the at least one vent-side particulateadsorbent volume or both have a flow restriction of less than 0.3 kPaunder 40 lpm air flow. In further embodiments, the at least onevent-side particulate adsorbent volume has a length to diameter ratio of2 or greater. In additional embodiments, the at least one fuel-sideadsorbent volume has a nominal BWC of greater than 8 g/dL, a nominal IACat 25° C. of more than 35 g/L between vapor concentrations of 5 vol %and 50 vol % n-butane, or both.

In a particular embodiment, the low retentivity particulate adsorbenthas a micropore volume of about 225 cc/L or less (about 0.5 cc/g orless). For example, the micropore volume of the low retentivityparticulate adsorbent may be less than or equal to about 200 cc/L, lessthan or equal to about 175 cc/L, less than or equal to about 150 cc/L,less than or equal to about 125 cc/L, less than or equal to about 100cc/L, less than or equal to about 75 cc/L, less than or equal to about50 cc/L, or less than or equal to about 25 cc/L. By way of furtherexample, the micropore volume of the low retentivity particulateadsorbent may be about 1.0 cc/L to about 225 cc/L, about 1.0 cc/L toabout 200 cc/L, about 1.0 cc/L to about 175 cc/L, about 1.0 cc/L toabout 150 cc/L, about 1.0 cc/L to about 125 cc/L, about 1.0 cc/L toabout 100 cc/L, about 1.0 cc/L to about 75 cc/L, about 1.0 cc/L to about50 cc/L, about 1.0 cc/L to about 25 cc/L, about 25 cc/L to about 225cc/L, about 25 cc/L to about 200 cc/L, about 25 cc/L to about 175 cc/L,about 25 cc/L to about 150 cc/L, about 25 cc/L to about 125 cc/L, about25 cc/L to about 100 cc/L, about 25 cc/L to about 75 cc/L, about 25 cc/Lto about 50 cc/L, about 50 cc/L to about 225 cc/L, about 50 cc/L toabout 200 cc/L, about 50 cc/L to about 175 cc/L, about 50 cc/L to about150 cc/L, about 50 cc/L to about 125 cc/L, about 50 cc/L to about 100cc/L, about 50 cc/L to about 75 cc/L, about 75 cc/L to about 225 cc/L,about 75 cc/L to about 200 cc/L, about 75 cc/L to about 175 cc/L, about75 cc/L to about 150 cc/L, about 75 cc/L to about 125 cc/L, about 75cc/L to about 100 cc/L, about 100 cc/L to about 225 cc/L, about 100 cc/Lto about 200 cc/L, about 100 cc/L to about 175 cc/L, about 100 cc/L toabout 150 cc/L, about 100 cc/L to about 125 cc/L, about 125 cc/L toabout 225 cc/L, about 125 cc/L to about 200 cc/L, about 125 cc/L toabout 175 cc/L, about 125 cc/L to about 150 cc/L, about 150 cc/L toabout 225 cc/L, about 150 cc/L to about 200 cc/L, about 150 cc/L toabout 175 cc/L, about 175 cc/L to about 225 cc/L, about 175 cc/L toabout 200 cc/L, or about 200 cc/L to about 225 cc/L.

In some other embodiments, the low retentivity particulate adsorbentcomprises a body defining an exterior surface and a three-dimensionallow flow resistance shape or morphology. The three-dimensional low flowresistance shape or morphology may be any shape or morphology that oneskilled in the art would appreciate has low flow resistance. Forexample, the three-dimensional low flow resistance shape or morphologymay be at least one of substantially a cylinder, substantially an ovalprism, substantially a sphere, substantially a cube, substantially anelliptical prism, substantially a rectangular prism, a lobed prism, athree-dimensional helix or spiral, or a combination thereof. Otheruseful examples of the morphology include shapes known to those skilledin the art of absorption column packings, and include Rachig rings,cross partition rings, Pall® rings, Intalox® saddles, Berl saddles,Super Intalox® saddles, Conjugate rings, Cascade mini rings, and Lessingrings. Other useful examples of the morphology include shapes known tothose skilled in the art of pasta making, and may include ribbon, solid,hollow, lobed, and lobed-hollow composite shapes of strips, springs,coils, corkscrews, shells, tubes, such as gemelli, fusilli, fusilli colbuco, macaroni, rigatoni, cellentani, farfalle, gomiti rigatti,casarecci, cavatelli, creste di galli, gigli, lumaconi, quadrefiore,radiatore, ruote, conchiglie, or a combination thereof.

By way of non-limiting examples, FIGS. 3A through 3I show exemplaryshape morphologies of the present disclosure, including a compositelobed shape (A), a square prism shape (B), a cylinder shape (C), a shapewith a star cross-section (D), a cross cross-section (E), a triangularprism with interior walls that transverse the center axis (F), atriangular prism with interior walls that do not transverse the centeraxis (G), a helical or twisted ribbon shape (H1 with an on-endappearance of H2), and a hollow cylinder (I).

The low retentivity particulate adsorbent material may have across-sectional width of about 1 mm to about 20 mm (e.g., about 1 mm,about 2 mm, about 3 mm, about 4 mm, about 5 mm, about 6 mm, about 7 mm,about 8 mm, about 9 mm, about 10 mm, about 11 mm, about 12 mm, about 13mm, about 14 mm, about 15 mm, about 16 mm about 17 mm, about 18 mm,about 19 mm, or about 20 mm). In a particulate embodiment, thecross-sectional width of the low retentivity particulate adsorbent isabout 1 mm to about 18 mm, about 1 mm to about 16 mm, about 1 mm toabout 14 mm, about 1 mm to about 12 mm, about 1 mm to about 10 mm, about1 mm to about 8 mm, about 1 mm to about 6 mm, about 1 mm to about 4 mm,about 1 mm to about 3 mm, about 2 mm to about 20 mm, about 2 mm to about18 mm, about 2 mm to about 16 mm, about 2 mm to about 14 mm, about 2 mmto about 12 mm, about 2 mm to about 10 mm, about 2 mm to about 8 mm,about 2 mm to about 6 mm, about 2 mm to about 4 mm, about 4 mm to about20 mm, about 4 mm to about 18 mm, about 4 mm to about 16 mm, about 4 mmto about 14 mm, about 4 mm to about 12 mm, about 4 mm to about 10 mm,about 4 mm to about 8 mm, about 4 mm to about 6 mm, about 6 mm to about20 mm, about 6 mm to about 18 mm, about 6 mm to about 16 mm, about 6 mmto about 14 mm, about 6 mm to about 12 mm, about 6 mm to about 10 mm,about 6 mm to about 8 mm, about 8 mm to about 20 mm, about 8 mm to about18 mm, about 8 mm to about 16 mm, about 8 mm to about 14 mm, about 8 mmto about 12 mm, about 8 mm to about 10 mm, about 10 mm to about 20 mm,about 10 mm to about 18 mm, about 10 mm to about 16 mm, about 10 mm toabout 14 mm, about 10 mm to about 12 mm, about 12 mm to about 20 mm,about 12 mm to about 18 mm, about 12 mm to about 16 mm, about 12 mm toabout 14 mm, about 14 to about 20 mm, about 14 mm to about 18 mm, about14 mm to about 16 mm, about 16 mm to about 20 mm, about 16 mm to about18 mm, or about 18 mm to about 20 mm.

The low retentivity particulate adsorbent may include at least onecavity in fluid communication with the exterior surface of theadsorbent.

The low retentivity particulate adsorbent may have a hollow shape incross section.

The low retentivity particulate adsorbent may include at least onechannel in fluid communication with at least one exterior surface.

In certain further embodiments, each part of the low retentivityparticulate adsorbent has a thickness equal to or less than about 3.0mm. For example, each part of the low retentivity particulate adsorbentmay have a thickness equal to or less than 2.5 mm, equal to or less than2.0 mm, equal to or less than 1.5 mm, equal to or less than 1.25 mm,equal to or less than 1.0 mm, equal to or less than 0.75 mm, equal to orless than 0.5 mm, or equal to or less than 0.25 mm. That is, each partof the adsorbent may have a thickness of about 0.1 mm to about 3 mm,about 0.1 mm to about 2.5 mm, about 0.1 mm to about 2.0 mm, about 0.1 mmto about 1.5 mm, about 0.1 mm to about 1.0 mm, about 0.1 mm to about 0.5mm, about 0.2 mm to about 3 mm, about 0.2 mm to about 2.5 mm, about 0.2mm to about 2.0 mm, about 0.2 mm to about 1.5 mm, about 0.2 mm to about1.0 mm, about 0.2 mm to about 0.5 mm, about 0.4 mm to about 3 mm, about0.4 mm to about 2.5 mm, about 0.4 mm to about 2.0 mm, about 0.4 mm toabout 1.5 mm, about 0.4 mm to about 1.0 mm, about 0.4 mm to about 3 mm,about 0.4 mm to about 2.5 mm, about 0.4 mm to about 2.0 mm, about 0.4 mmto about 1.5 mm, about 0.4 mm to about 1.0 mm, about 0.75 mm to about 3mm, about 0.75 mm to about 2.5 mm, about 0.75 mm to about 2.0 mm, about0.75 mm to about 1.5 mm, about 0.75 mm to about 1.0 mm, about 1.25 mm toabout 3 mm, about 1.25 mm to about 2.5 mm, about 1.25 mm to about 2.0mm, about 2.0 mm to about 3 mm, about 2.0 mm to about 2.5 mm, or about2.5 mm to about 3.0 mm.

In an embodiment, at least one exterior wall of the hollow shape of thelow retentivity particulate adsorbent has a thickness equal to or lessthan about 1.0 mm (e.g., about 0.1 mm, about 0.2 mm, about 0.3 mm, about0.4 mm, about 0.5 mm, about 0.6 mm, about 0.7 mm, about 0.8 mm, about0.9 mm, or about 1.0 mm). For example, an exterior wall of the hollowshape of the low retentivity particulate adsorbent may have a thicknessin a range of about 0.1 mm to about 1.0 mm, about 0.1 mm to about 0.9mm, about 0.1 mm to about 0.8 mm, about 0.1 mm to about 0.7 mm, about0.1 mm to about 0.6 mm, about 0.1 mm to about 0.5 mm, about 0.1 mm toabout 0.4 mm, about 0.1 mm to about 0.3 mm, about 0.1 mm to about 0.2mm, about 0.2 mm to about 1.0 mm, about 0.2 mm to about 0.9 mm, about0.2 mm to about 0.8 mm, about 0.2 mm to about 0.7 mm, about 0.2 mm toabout 0.6 mm, about 0.2 mm to about 0.5 mm, about 0.2 mm to about 0.4mm, about 0.2 mm to about 0.3 mm, about 0.3 mm to about 1.0 mm, about0.3 mm to about 0.9 mm, about 0.3 mm to about 0.8 mm, about 0.3 mm toabout 0.7 mm, about 0.3 mm to about 0.6 mm, about 0.3 mm to about 0.5mm, about 0.3 mm to about 0.4 mm, about 0.4 mm to about 1.0 mm, about0.4 mm to about 0.9 mm, about 0.4 mm to about 0.8 mm, about 0.4 mm toabout 0.7 mm, about 0.4 mm to about 0.6 mm, about 0.4 mm to about 0.5mm, about 0.5 mm to about 1.0 mm, about 0.5 mm to about 0.9 mm, about0.5 mm to about 0.8 mm, about 0.5 mm to about 0.7 mm, about 0.5 mm toabout 0.6 mm, about 0.6 mm to about 1.0 mm, about 0.6 mm to about 0.9mm, about 0.6 mm to about 0.8 mm, about 0.6 mm to about 0.7 mm, about0.7 mm to about 1.0 mm, about 0.7 mm to about 0.9 mm, about 0.7 mm toabout 0.8 mm, about 0.8 mm to about 1.0 mm, about 0.8 mm to about 0.9mm, or about 0.9 mm to about 1.0 mm.

In yet other embodiments, the hollow shape of the low retentivityparticulate adsorbent has at least one interior wall extending betweenthe exterior walls and having a thickness equal to or less than about1.0 mm (e.g., about 0.1 mm, about 0.2 mm, about 0.3 mm, about 0.4 mm,about 0.5 mm, about 0.6 mm, about 0.7 mm, about 0.8 mm, about 0.9 mm, orabout 1.0 mm). For example, an interior wall may have a thickness in arange of about 0.1 mm to about 1.0 mm, about 0.1 mm to about 0.9 mm,about 0.1 mm to about 0.8 mm, about 0.1 mm to about 0.7 mm, about 0.1 mmto about 0.6 mm, about 0.1 mm to about 0.5 mm, about 0.1 mm to about 0.4mm, about 0.1 mm to about 0.3 mm, about 0.1 mm to about 0.2 mm, about0.2 mm to about 1.0 mm, about 0.2 mm to about 0.9 mm, about 0.2 mm toabout 0.8 mm, about 0.2 mm to about 0.7 mm, about 0.2 mm to about 0.6mm, about 0.2 mm to about 0.5 mm, about 0.2 mm to about 0.4 mm, about0.2 mm to about 0.3 mm, about 0.3 mm to about 1.0 mm, about 0.3 mm toabout 0.9 mm, about 0.3 mm to about 0.8 mm, about 0.3 mm to about 0.7mm, about 0.3 mm to about 0.6 mm, about 0.3 mm to about 0.5 mm, about0.3 mm to about 0.4 mm, about 0.4 mm to about 1.0 mm, about 0.4 mm toabout 0.9 mm, about 0.4 mm to about 0.8 mm, about 0.4 mm to about 0.7mm, about 0.4 mm to about 0.6 mm, about 0.4 mm to about 0.5 mm, about0.5 mm to about 1.0 mm, about 0.5 mm to about 0.9 mm, about 0.5 mm toabout 0.8 mm, about 0.5 mm to about 0.7 mm, about 0.5 mm to about 0.6mm, about 0.6 mm to about 1.0 mm, about 0.6 mm to about 0.9 mm, about0.6 mm to about 0.8 mm, about 0.6 mm to about 0.7 mm, about 0.7 mm toabout 1.0 mm, about 0.7 mm to about 0.9 mm, about 0.7 mm to about 0.8mm, about 0.8 mm to about 1.0 mm, about 0.8 mm to about 0.9 mm, or about0.9 mm to about 1.0 mm.

In a particular embodiment, the thickness of at least one of theinterior wall, the exterior wall, or a combination thereof, of the lowretentivity particulate adsorbent is equal to or less than about 1.0 mm(e.g., about 0.1 mm, about 0.2 mm, about 0.3 mm, about 0.4 mm, about 0.5mm, about 0.6 mm, about 0.7 mm, about 0.8 mm, about 0.9 mm, or about 1.0mm). For example, the thickness of at least one of the interior wall,the exterior wall, or a combination thereof, of the low retentivityparticulate adsorbent is equal to or less than about 1.0 mm, equal to orless than about 0.6 mm, or equal to or less than about 0.4 mm. Incertain embodiments, at least one of the interior wall, the exteriorwall, or a combination thereof, of the low retentivity particulateadsorbent has a thickness in a range of about 0.1 mm to about 1.0 mm,about 0.1 mm to about 0.9 mm, about 0.1 mm to about 0.8 mm, about 0.1 mmto about 0.7 mm, about 0.1 mm to about 0.6 mm, about 0.1 mm to about 0.5mm, about 0.1 mm to about 0.4 mm, about 0.1 mm to about 0.3 mm, about0.1 mm to about 0.2 mm, about 0.2 mm to about 1.0 mm, about 0.2 mm toabout 0.9 mm, about 0.2 mm to about 0.8 mm, about 0.2 mm to about 0.7mm, about 0.2 mm to about 0.6 mm, about 0.2 mm to about 0.5 mm, about0.2 mm to about 0.4 mm, about 0.2 mm to about 0.3 mm, about 0.3 mm toabout 1.0 mm, about 0.3 mm to about 0.9 mm, about 0.3 mm to about 0.8mm, about 0.3 mm to about 0.7 mm, about 0.3 mm to about 0.6 mm, about0.3 mm to about 0.5 mm, about 0.3 mm to about 0.4 mm, about 0.4 mm toabout 1.0 mm, about 0.4 mm to about 0.9 mm, about 0.4 mm to about 0.8mm, about 0.4 mm to about 0.7 mm, about 0.4 mm to about 0.6 mm, about0.4 mm to about 0.5 mm, about 0.5 mm to about 1.0 mm, about 0.5 mm toabout 0.9 mm, about 0.5 mm to about 0.8 mm, about 0.5 mm to about 0.7mm, about 0.5 mm to about 0.6 mm, about 0.6 mm to about 1.0 mm, about0.6 mm to about 0.9 mm, about 0.6 mm to about 0.8 mm, about 0.6 mm toabout 0.7 mm, about 0.7 mm to about 1.0 mm, about 0.7 mm to about 0.9mm, about 0.7 mm to about 0.8 mm, about 0.8 mm to about 1.0 mm, about0.8 mm to about 0.9 mm, or about 0.9 mm to about 1.0 mm.

In some embodiments, the interior wall of the low retentivityparticulate adsorbent extends outward to the exterior wall in at leasttwo directions from a hollow portion of the particulate adsorbentmaterial (such as, from a center of the particulate adsorbent material).

For example, the interior walls of the low retentivity particulateadsorbent may extend outward to the exterior wall in at least threedirections from a hollow portion of the particulate adsorbent material(such as, from a center of the particulate adsorbent material) or atleast four directions from a hollow portion of the particulate adsorbentmaterial (such as, from a center of the particulate adsorbent material).

In certain embodiments, the low retentivity particulate adsorbentmaterial may have a length of about 1 mm to about 20 mm (e.g., about 1mm, about 2 mm, about 3 mm, about 4 mm, about 5 mm, about 6 mm, about 7mm, about 8 mm, about 9 mm, about 10 mm, about 11 mm, about 12 mm, about13 mm, about 14 mm, about 15 mm, about 16 mm about 17 mm, about 18 mm,about 19 mm, or about 20 mm). In a particular embodiment, the length ofthe low retentivity particulate adsorbent is about 1 mm to about 18 mm,about 1 mm to about 16 mm, about 1 mm to about 14 mm, about 1 mm toabout 12 mm, about 1 mm to about 10 mm, about 1 mm to about 8 mm, about1 mm to about 6 mm, about 1 mm to about 4 mm, about 1 mm to about 3 mm,about 2 mm to about 20 mm, about 2 mm to about 18 mm, about 2 mm toabout 16 mm, about 2 mm to about 14 mm, about 2 mm to about 12 mm, about2 mm to about 10 mm, about 2 mm to about 8 mm, about 2 mm to about 6 mm,about 2 mm to about 4 mm, about 4 mm to about 20 mm, about 4 mm to about18 mm, about 4 mm to about 16 mm, about 4 mm to about 14 mm, about 4 mmto about 12 mm, about 4 mm to about 10 mm, about 4 mm to about 8 mm,about 4 mm to about 6 mm, about 6 mm to about 20 mm, about 6 mm to about18 mm, about 6 mm to about 16 mm, about 6 mm to about 14 mm, about 6 mmto about 12 mm, about 6 mm to about 10 mm, about 6 mm to about 8 mm,about 8 mm to about 20 mm, about 8 mm to about 18 mm, about 8 mm toabout 16 mm, about 8 mm to about 14 mm, about 8 mm to about 12 mm, about8 mm to about 10 mm, about 10 mm to about 20 mm, about 10 mm to about 18mm, about 10 mm to about 16 mm, about 10 mm to about 14 mm, about 10 mmto about 12 mm, about 12 mm to about 20 mm, about 12 mm to about 18 mm,about 12 mm to about 16 mm, about 12 mm to about 14 mm, about 14 toabout 20 mm, about 14 mm to about 18 mm, about 14 mm to about 16 mm,about 16 mm to about 20 mm, about 16 mm to about 18 mm, or about 18 mmto about 20 mm.

The low retentivity particulate adsorbent may further comprise at leastone of: a pore forming material or processing aid that sublimates,vaporizes, chemically decomposes, solubilizes, or melts when heated to atemperature of 100° C. or more; a binder; a filler; or a combinationthereof.

In a particular embodiment, the low retentivity particulate adsorbentcomprises at least one of: about 5% to about 60% of adsorbent, about 60%or less of a filler, about 6% or less of the pore forming material (orprocessing aid), about 10% or less of silicate, about 5% to about 70% ofclay, or a combination thereof. The low retentivity particulateadsorbent may be present in about 5% to about 60%, about 5% to about50%, about 5% to about 40%, about 5% to about 30%, about 5% to about20%, about 5% to about 10%, about 10% to about 60%, about 10% to about50%, about 10% to about 40%, about 10% to about 30%, about 10% to about20%, about 20% to about 60%, about 20% to about 50%, about 20% to about40%, about 20% to about 30%, about 30% to about 60%, about 30% to about50%, about 30% to about 40%, about 40% to about 60%, about 40% to about50%, or about 50% to about 60% of the particulate adsorbent material.

The filler may be present in the low retentivity particulate adsorbentin less than or equal to about 60%, less than or equal to about 50%,less than or equal to about 40%, less than or equal to about 30%, lessthan or equal to about 20%, less than or equal to about 10%, about 5% toabout 60%, about 5% to about 50%, about 5% to about 40%, about 5% toabout 30%, about 5% to about 20%, about 5% to about 10%, about 10% toabout 60%, about 10% to about 50%, about 10% to about 40%, about 10% toabout 30%, about 10% to about 20%, about 20% to about 60%, about 20% toabout 50%, about 20% to about 40%, about 20% to about 30%, about 30% toabout 60%, about 30% to about 50%, about 30% to about 40%, about 40% toabout 60%, about 40% to about 50%, or about 50% to about 60% of theparticulate adsorbent material.

The pore forming material of the low retentivity particulate adsorbentmay be present in ≤about 6%, ≤about 5%, ≤about 4%, ≤about 3%, ≤about 2%,or ≤about 1% of the particulate adsorbent material.

The silicate of the low retentivity particulate adsorbent may be presentin ≤about 10%, ≤about 9%, ≤about 8%, ≤about 7%, ≤about 6%, ≤about 5%,≤about 4%, ≤about 3%, ≤about 2%, or ≤about 1% of the particulateadsorbent material.

The clay of the low retentivity particulate adsorbent may be present inabout 5% to about 70%, 5% to about 60%, about 5% to about 50%, about 5%to about 40%, about 5% to about 30%, about 5% to about 20%, about 5% toabout 10%, about 10% to about 70%, about 10% to about 60%, about 10% toabout 50%, about 10% to about 40%, about 10% to about 30%, about 10% toabout 20%, about 20% to about 70%, about 20% to about 60%, about 20% toabout 50%, about 20% to about 40%, about 20% to about 30%, about 30% toabout 70%, about 30% to about 60%, about 30% to about 50%, about 30% toabout 40%, about 40% to about 70%, about 40% to about 60%, about 40% toabout 50%, about 50% to about 70%, about 50% to about 60%, or about 60%to about 70% of the particulate adsorbent material.

The pore forming material (or processing aid) of the low retentivityparticulate adsorbent produces macroscopic pores when it is sublimated,vaporized, chemically decomposed, solubilized, or melted. This providesa spatial dilution of the low retentivity particulate adsorbentmaterial. The pore forming material may be a cellulose derivative, suchas methylcellulose, carboxymethyl cellulose, polyethylene glycol,phenol-formaldehyde resins (novolac, resole), polyethylene or polyesterresins. The cellulose derivative may include copolymers with methylgroups and/or partial substitutions with hydroxypropyl and/orhydroxyethyl groups. The pore forming material or processing aid maysublimate, vaporize, chemically decompose, solubilize, or melt whenheated to a temperature in a range of about 125° C. to about 640° C. Forexample, the processing aid of the low retentivity particulate adsorbentmay sublimate, vaporize, chemically decompose, solubilize, or melt whenheated to a temperature in a range of about 125° C. to about 600° C.,about 125° C. to about 550° C., about 125° C. to about 500° C., about125° C. to about 450° C., about 125° C. to about 400° C., about 125° C.to about 350° C., about 125° C. to about 300° C., about 125° C. to about250° C., about 125° C. to about 200° C., about 125° C. to about 150° C.,about 150° C. to about 640° C., 150° C. to about 600° C., about 150° C.to about 550° C., about 150° C. to about 500° C., about 150° C. to about450° C., about 150° C. to about 400° C., about 150° C. to about 350° C.,about 150° C. to about 300° C., about 150° C. to about 250° C., about150° C. to about 200° C., about 200° C. to about 640° C., 200° C. toabout 600° C., about 200° C. to about 550° C., about 200° C. to about500° C., about 200° C. to about 450° C., about 200° C. to about 400° C.,about 200° C. to about 350° C., about 200° C. to about 300° C., about200° C. to about 250° C., about 250° C. to about 640° C., 250° C. toabout 600° C., about 250° C. to about 550° C., about 250° C. to about500° C., about 250° C. to about 450° C., about 250° C. to about 400° C.,about 250° C. to about 350° C., about 250° C. to about 300° C., about300° C. to about 640° C., 300° C. to about 600° C., about 300° C. toabout 550° C., about 300° C. to about 500° C., about 300° C. to about450° C., about 300° C. to about 400° C., about 300° C. to about 350° C.,about 350° C. to about 640° C., 350° C. to about 600° C., about 350° C.to about 550° C., about 350° C. to about 500° C., about 350° C. to about450° C., about 350° C. to about 400° C., about 400° C. to about 640° C.,400° C. to about 600° C., about 400° C. to about 550° C., about 400° C.to about 500° C., about 400° C. to about 450° C., about 450° C. to about640° C., 450° C. to about 600° C., about 450° C. to about 550° C., about450° C. to about 500° C., about 500° C. to about 640° C., 500° C. toabout 600° C., about 500° C. to about 550° C., about 550° C. to about640° C., 550° C. to about 600° C., or about 600° C. to about 640° C.

The binder of the low retentivity particulate adsorbent may be a clay ora silicate material. For example, the binder of the low retentivityparticulate adsorbent may be at least one of Zeolite clay, Bentoniteclay, Montmorillonite clay, Illite clay, French Green clay, Pascaliteclay, Redmond clay, Terramin clay, Living clay, Fuller's Earth clay,Ormalite clay, Vitallite clay, Rectorite clay, Cordierite, ball clay,kaolin or a combination thereof.

The filler of the low retentivity particulate adsorbent may function inthe particulate adsorbent structure for aiding and preserving shapeformation and mechanical integrity, and for enhancing the amount ofmacropore volume in the final particulate product. In an embodiment, thefiller of the low retentivity particulate adsorbent is solid or hollowmicrospheres, which may be of micron size or larger. In otherembodiments, the filler of the low retentivity particulate adsorbent isan inorganic filler, such as a glass material and/or a ceramic material.The filler of the low retentivity particulate adsorbent may be anyappropriate filler, which one skilled in the art would appreciate, thatprovides the above benefits.

The low retentivity particulate adsorbent material may be prepared byadmixing an adsorbent with microscopic pores having a diameter less thanabout 100 nm and a pore forming material or processing aid thatsublimates, vaporizes, chemically decomposes, solubilizes, or melts whenheated to a temperature of 100° C. or more; and heating the mixture to atemperature in a range of about 100° C. to about 1200° C. for about 0.25hours to about 24 hours forming macroscopic pores having a diameter ofabout 100-100,000 nm when the core material is sublimated, vaporized,chemically decomposed, solubilized, or melted, wherein a ratio of avolume of the macroscopic pore to a volume of the microscopic pore inthe adsorbent is greater than 150%. The adsorbent may have any of thecharacteristics of the low retentivity particulate adsorbent materialdiscussed throughout the present disclosure.

The mixture may be heated to about 100° C. to about 1200° C., about 100°C. to about 1000° C., about 100° C. to about 900° C., about 100° C. toabout 800° C., about 100° C. to about 700° C., about 100° C. to about600° C., about 100° C. to about 500° C., about 100° C. to about 400° C.,about 100° C. to about 300° C., about 100° C. to about 200° C., about200° C. to about 1200° C., about 200° C. to about 1100° C., about 200°C. to about 1000° C., about 200° C. to about 900° C., about 200° C. toabout 800° C., about 200° C. to about 700° C., about 200° C. to about600° C., about 200° C. to about 500° C., about 200° C. to about 400° C.,about 200° C. to about 300° C., about 300° C. to about 1200° C., about300° C. to about 1100° C., about 300° C. to about 1000° C., about 300°C. to about 900° C., about 300° C. to about 800° C., about 300° C. toabout 700° C., about 300° C. to about 600° C., about 300° C. to about500° C., about 300° C. to about 400° C., about 400° C. to about 1200°C., about 400° C. to about 1100° C., about 400° C. to about 1000° C.,about 400° C. to about 900° C., about 400° C. to about 800° C., about400° C. to about 700° C., about 400° C. to about 600° C., about 400° C.to about 500° C., about 500° C. to about 1200° C., about 500° C. toabout 1100° C., about 500° C. to about 1000° C., about 500° C. to about900° C., about 500° C. to about 800° C., about 500° C. to about 700° C.,about 500° C. to about 600° C., about 600° C. to about 1200° C., about600° C. to about 1100° C., about 600° C. to about 1000° C., about 600°C. to about 900° C., about 600° C. to about 800° C., about 600° C. toabout 700° C., about 700° C. to about 1200° C., about 700° C. to about1100° C., about 700° C. to about 1000° C., about 700° C. to about 900°C., about 700° C. to about 800° C., about 800° C. to about 1200° C.,about 800° C. to about 1100° C., about 800° C. to about 1000° C., about800° C. to about 900° C., about 900° C. to about 1200° C., about 900° C.to about 1100° C., about 900° C. to about 1000° C., about 1000° C. toabout 1200° C., about 1000° C. to about 1100° C., or about 1100° C. toabout 1200° C.

In some embodiments, heating the mixture may include a ramp rate ofabout 2.5° C./minute, about 1.0° C./minute, about 1.25° C./minute, about1.5° C./minute, about 1.75° C./minute, about 2.0° C./minute, about 2.25°C./minute, about 2.75° C./minute, about 3.0° C./minute, about 3.25°C./minute, about 3.5° C./minute, about 3.75° C./minute, about 4.0°C./minute, or 4.25° C./minute. For example, the ramp rate may be about0.5° C./minute to about 20° C./minute, about 0.5° C./minute to about 15°C./minute, about 0.5° C./minute to about 10° C./minute, about 0.5°C./minute to about 5.0° C./minute, about 0.5° C./minute to about 2.5°C./minute, about 1.0° C./minute to about 20° C./minute, about 1.0°C./minute to about 15° C./minute, about 1.0° C./minute to about 10°C./minute, about 1.0° C./minute to about 5.0° C./minute, about 1.0°C./minute to about 2.5° C./minute, about 2.0° C./minute to about 20°C./minute, about 2.0° C./minute to about 15° C./minute, about 2.0°C./minute to about 10° C./minute, about 2.0° C./minute to about 5.0°C./minute, about 2.0° C./minute to about 2.5° C./minute, about 5.0°C./minute to about 20° C./minute, about 5.0° C./minute to about 15°C./minute, about 5.0° C./minute to about 10° C./minute, about 10°C./minute to about 20° C./minute, about 10° C./minute to about 15°C./minute, or about 15° C./minute to about 20° C./minute. In certainembodiments, the heating ramp rate is from about 20° C./minute to about100° C./minute, 30° C./minute to about 100° C./minute, 40° C./minute toabout 100° C./minute, 50° C./minute to about 100° C./minute, 60°C./minute to about 100° C./minute, 70° C./minute to about 100°C./minute, 80° C./minute to about 100° C./minute, or 90° C./minute toabout 100° C./minute.

For example, the ramp to the temperature may take about 5 minutes toabout 2 hours, about 5 minutes to about 1.75 hours, about 5 minutes toabout 1.5 hours, about 5 minutes to about 1.25 hours, about 5 minutes toabout 1.0 hours, about 5 minutes to about 45 minutes, about 5 minutes toabout 30 minutes, about 5 minutes to about 15 minutes, about 15 minutesto about 2 hours, about 15 minutes to about 1.75 hours, about 15 minutesto about 1.5 hours, about 15 minutes to about 1.25 hours, about 15minutes to about 1.0 hours, about 15 minutes to about 45 minutes, about15 minutes to about 30 minutes, about 30 minutes to about 2 hours, about30 minutes to about 1.75 hours, about 30 minutes to about 1.5 hours,about 30 minutes to about 1.25 hours, about 30 minutes to about 1.0hours, about 30 minutes to about 45 minutes, about 45 minutes to about 2hours, about 45 minutes to about 1.75 hours, about 45 minutes to about1.5 hours, about 45 minutes to about 1.25 hours, about 45 minutes toabout 1.0 hours, about 1.0 hours to about 2 hours, about 1.0 hours toabout 1.75 hours, about 1.0 hours to about 1.5 hours, about 1.0 to about1.25 hours, about 1.25 to about 2 hours, about 1.25 to about 1.75 hours,about 1.25 to about 1.5 hours, about 1.5 to about 2 hours, about 1.5 toabout 1.75 hours, or about 1.75 hours to about 2.0 hours.

In another embodiment, the mixture is held at the temperature (i.e.,after the ramp) for about 0.25 hours to about 24 hours. For example, themixture may be held at the temperature for about 0.25 hours to about 18hours, about 0.25 hours to about 16 hours, about 0.25 hours to about 14hours, about 0.25 hours to about 12 hours, about 0.25 hours to about 10hours, about 0.25 hours to about 8 hours, about 0.25 hours to about 6hours, about 0.25 hours to about 4 hours, about 0.25 hours to about 2hours, about 1 hour to about 24 hours, about 0.25 hours to about 18hours, about 1 hour to about 16 hours, about 1 hour to about 14 hours,about 1 hour to about 12 hours, about 1 hour to about 10 hours, about 1hour to about 8 hours, about 1 hour to about 6 hours, about 1 hour toabout 4 hours, about 1 hour to about 2 hours, about 2 hours to about 24hours, about 2 hours to about 18 hours, about 2 hours to about 16 hours,about 2 hours to about 14 hours, about 2 hours to about 12 hours, about2 hours to about 10 hours, about 2 hours to about 8 hours, about 2 hoursto about 6 hours, about 2 hours to about 3 hours, about 3 hours to about24 hours, about 3 hours to about 18 hours, about 3 hours to about 16hours, about 3 hours to about 14 hours, about 3 hours to about 12 hours,about 3 hours to about 10 hours, about 3 hours to about 8 hours, about 3hours to about 6 hours, about 3 hours to about 4 hours, about 4 hours toabout 24 hours, about 4 hours to about 18 hours, about 4 hours to about16 hours, about 4 hours to about 14 hours, about 4 hours to about 12hours, about 4 hours to about 10 hours, about 4 hours to about 8 hours,about 4 hours to about 6 hours, about 6 hours to about 24 hours, about 6hours to about 18 hours, about 6 hours to about 16 hours, about 6 hoursto about 14 hours, about 6 hours to about 12 hours, about 6 hours toabout 10 hours, about 6 hours to about 8 hours, about 8 hours to about24 hours, about 8 hours to about 18 hours, about 8 hours to about 16hours, about 8 hours to about 14 hours, about 8 hours to about 12 hours,about 8 hours to about 10 hours, about 10 hours to about 24 hours, about10 hours to about 18 hours, about 10 hours to about 16 hours, about 10hours to about 14 hours, about 10 hours to about 12 hours, about 12hours to about 24 hours, about 12 hours to about 18 hours, about 12hours to about 16 hours, about 12 hours to about 14 hours, about 14hours to about 24 hours, about 14 hours to about 18 hours, about 14hours to about 16 hours, about 16 hours to about 24 hours, about 16hours to about 18 hours, about 18 hours to about 24 hours, about 18hours to about 22 hours, about 18 hours to about 20 hours, about 20hours to about 24 hours, about 20 hours to about 22 hours, or about 22hours to about 24 hours.

The method of making the low retentivity particulate adsorbent mayfurther comprise cooling the mixture (e.g., to about room temperature).In an embodiment, the mixture may be cooled over about 0.5 to about 10hours. For example, the mixture may be cooled over about 0.5 hours toabout 9 hours, about 0.5 hours to about 8 hours, about 0.5 hours toabout 7 hours, about 0.5 hours to about 6 hours, about 0.5 hours toabout 5 hours, about 0.5 hours to about 4 hours, about 0.5 hours toabout 3 hours, about 0.5 hours to about 2 hours, about 0.5 hours toabout 1 hour, about 5 hours to about 10 hours, about 5 hours to about 9hours, about 5 hours to about 8 hours, about 5 hours to about 7 hours,about 5 hours to about 6 hours, about 6 hours to about 10 hours, about 6hours to about 9 hours, about 6 hours to about 8 hours, about 6 hours toabout 7 hours, about 7 hours to about 10 hours, about 7 hours to about 9hours, about 7 hours to about 8 hours, about 8 hours to about 10 hours,about 8 hours to about 9 hours, or about 9 hours to about 10 hours.

Heating of the mixture for making the low retentivity particulateadsorbent may be performed in an inert atmosphere (e.g., nitrogen,argon, neon, krypton, xenon, radon, flue gas wherein the steam andoxygen content are controlled, or a combination thereof).

The low retentivity particulate adsorbent material may have aretentivity of about 1.0 g/dL or less, about 0.75 g/dL or less, about0.50 g/dL or less, or about 0.25 g/dL or less. For example, the lowretentivity adsorbent may have a retentivity of about 0.25 g/dL to about1.00 g/dL, about 0.25 g/dL to about 0.75 g/dL, about 0.25 g/dL to about0.50 g/dL, about 0.50 g/dL to about 1.00 g/dL, about 0.50 g/dL to about0.75 g/dL, or about 0.75 g/dL to about 1.00 g/dL.

In any aspect or embodiment described herein, at least one of thediameter of the microscopic pores of the low retentivity adsorbent isless than about 100 nm, the diameter of the macroscopic pores is equalto or greater than 100 nm and less than 100,000 nm, or a combinationthereof.

The method of making the low retentivity particulate adsorbent mayfurther comprise extruding or compressing the admix into a shapedstructure. For example, the extruded or compressed low retentivityparticulate adsorbent material may comprise a body defining an exteriorsurface and a three-dimensional low flow resistant shape or morphology.The low flow resistant shape or morphology of the low retentivityparticulate adsorbent can be, e.g., any shape or morphology describedherein for the adsorbent material. For example, the three-dimensionallow flow resistant shape or morphology of the low retentivityparticulate adsorbent may be at least one of substantially a cylinder,substantially an oval prism, substantially a sphere, substantially acube, substantially an elliptical prism, substantially a rectangularprism, a lobed prism, a three-dimensional spiral, the shape ormorphology illustrated in FIGS. 3A through 3I, or a combination thereof.

The adsorbent of the low retentivity particulate adsorbent may be atleast one of activated carbon, molecular sieves, porous alumina, clay,porous silica, zeolites, metal organic frameworks, or a combinationthereof.

The mixture of the low retentivity particulate adsorbent may furthercomprise a binder (such as clay, silicate or a combination thereof),and/or a filler. The filler may be any filled known or that becomesknown in the relevant art.

The low retentivity particulate adsorbent may have a cross-sectionalwidth in a range of about 1 mm to about 20 mm.

The low retentivity particulate adsorbent material may include at leastone cavity or channel in fluid communication with an exterior surface ofthe adsorbent. The low retentivity particulate adsorbent may have ahollow shape in cross section. Each part of the low retentivityparticulate adsorbent may have a thickness of about 3.0 mm or less. Anexterior wall of the hollow shape may have a thickness that is 3 mm orless (e.g., about 0.1 mm to about 1.0 mm). The hollow shape may haveinterior walls extending between the exterior walls, which may have,e.g., a thickness of about 3.0 mm or less (e.g., about 0.1 mm to about1.0 mm).

The interior walls may extend outward to the exterior wall in at leasttwo directions, at least three directs, or at least four directions fromthe interior volume (such as, from the hollow portion), such as acenter.

In some embodiments, the low retentivity particulate adsorbent has alength of about 1 mm to about 20 mm (e.g., about 2 mm to about 7 mm).

Methods

In a further aspect, the present disclosure provides a method forreducing fuel vapor emissions in an evaporative emission control system,the method comprising contacting the fuel vapor with at least one volumeof a vent-side particulate adsorbent comprising microscopic pores with adiameter of less than about 100 nm, macroscopic pores having a diameterof about 100-100,000 nm, and a ratio of a volume of the macroscopicpores to a volume of the microscopic pores (M/m) that is greater thanabout 150%, wherein the at least one vent-side particulate adsorbentvolume has a butane retentivity of from about 1 g/dL to about 0.25 g/dLor less, a particle diameter of from 3-6 mm or both.

In some embodiments, the method further comprises contacting the fuelvapor with at least one fuel-side adsorbent volume, e.g., a high BWC,high IAC adsorbent volume as described herein, prior to contacting theat least one vent-side particulate adsorbent as described herein.

In any of the aspects or embodiments described herein, the adsorbentsare located within a single canister. In particular embodiments, theadsorbents are located within a plurality of canisters that areconnected to permit sequential contact by the fuel vapor.

In a further embodiment, the method may comprises contacting the fuelvapor with a high butane working capacity adsorbent volume as describedherein, prior to a vent-side low retentivity particulate adsorbentvolume. That is, the high butane working capacity adsorbent is locatedupstream in the fuel vapor flow path relative to the low retentivityparticulate adsorbent. For example, if a vent-side low retentivityparticulate adsorbent volume is present in volume 204 of the maincanister, the high butane working capacity adsorbent can be present inat least one of the volumes 203, 202, 201, or a combination thereof ofthe main canister. Similarly, if the supplemental canister comprises avent-side low retentivity particulate adsorbent volume, the high butaneworking capacity adsorbent can be located in at least one volume of themain canister 201-204 and/or at least one volume of the supplementalcanister prior to or upstream of the supplemental canister vent-side lowretentivity particulate adsorbent volume. For example, if the vent-sidelow retentivity particulate adsorbent volume is present in volume 304,then high butane working capacity adsorbent can be present in at leastone volume selected from 201-204, 301-303, or combinations thereof. Oneskilled in the art will appreciate that there are numerous otherconfigurations that meet this feature. For example, in an embodiment,the main canister comprises high butane working capacity adsorbent (suchas, in at least one of the volumes 201-204, or combinations thereof),while the supplemental canister comprises high butane adsorbent (suchas, in at least one of the volumes 301-305, or combinations thereof).

The method may further comprise contacting the fuel vapor with anadditional vent-side particulate adsorbent volume, e.g., vent-side lowretentivity particulate adsorbent volume that is downstream from orsubsequent to another in the fluid or vapor path, wherein the vent-sidesubsequent adsorbent has microscopic pores with a diameter of less thanabout 100 nm, macroscopic pores having a diameter of about 100-100,000nm, and a ratio of a volume of the macroscopic pores to a volume of themicroscopic pores that is equal to or less than about 150%. For example,if volume 203 of the main canister comprises low retentivity particulateadsorbent, then the downstream vent-side subsequent adsorbent volumecould be present in volume 204 of the main canister, at least one volumeof a supplemental canister 301-305, or a combination thereof. Forexample, in a particular embodiment, low retentivity particulateadsorbent is present in the main canister side of the supplementalcanister (e.g., 301-303) and the downstream/subsequent adsorbent volumeis present on the vent port side of the supplemental canister (e.g.,volumes 304 and 305).

As such, in certain embodiments, the method comprises contacting thehigh butane working capacity adsorbent/volume, the low retentivityadsorbent/volume, and the subsequent adsorbent/volume to fuel vapor fromthe fuel vapor inlet in that order.

As such, in certain embodiments, the method comprises contacting thehigh butane working capacity adsorbent/volume, the low retentivityadsorbent/volume, and the subsequent adsorbent/volume to fuel vapor fromthe fuel vapor inlet in that order.

The adsorbents suitable for use in the adsorbent volumes may be derivedfrom many different materials and in various forms. It may be a singlecomponent or a blend of different components. Furthermore, the adsorbent(either as a single component or a blend of different components) mayinclude a volumetric diluent. Non-limiting examples of the volumetricdiluents may include, but are not limited to, spacer, inert gap, foams,fibers, springs, or combinations thereof.

EXAMPLES

Determination of Apparent Density

The standard method ASTM D 2854-09(2014) (hereinafter “the StandardMethod”) may be used to determine the apparent density of particulateadsorbents, taking into account the prescribed minimum ratio of 10 forthe measuring cylinder diameter to mean particle diameter of theparticulate material, with mean particle diameter measured according tothe prescribed standard screening method.

Determination of Macroscopic Pore Volume

Macroscopic pore volume is measured by mercury intrusion porosimetrymethod ISO 15901-1:2016. The equipment used for the examples was aMicromeritics Autopore V (Norcross, Ga.). Samples used were around 0.4 gin size and pre-treated for at least 1 hour in an oven at 105° C. Thesurface tension of mercury and contact angle used for the Washburnequation were 485 dynes/cm and 130°, respectively. Macropores asreferred to herein, are those that have a diameter of from about 100 nmto about 100,000 nm.

Determination of Microscopic Pore Volume

Microscopic pore volume is measured by nitrogen adsorption porosimetryby the nitrogen gas adsorption method ISO 15901-2:2006 using aMicromeritics ASAP 2420 (Norcross, Ga.). Micropores as referred toherein, are pores with a diameter of less than about 100 nm. The samplepreparation procedure was to degas to a pressure of less than 10 μmHg.The determination of pore volumes for the microscopic pore sizes wasfrom the desorption branch of the 77 K isotherm for a 0.1 g sample. Thenitrogen adsorption isotherm data was analyzed by the Kelvin and Halseyequations to determine the distribution of pore volume with pore size ofcylindrical pores according to the model of Barrett, Joyner, and Halenda(“BJH”). The non-ideality factor was 0.0000620. The density conversionfactor was 0.0015468. The thermal transpiration hard-sphere diameter was3.860 Å. The molecular cross-sectional area was 0.162 nm². The condensedlayer thickness (Å) related to pore diameter (D, Å) used for thecalculations was 0.4977 [ln(D)]²−0.6981 ln(D)+2.5074. Target relativepressures for the isotherm were the following: 0.04, 0.05, 0.085, 0.125,0.15, 0.18, 0.2, 0.355, 0.5, 0.63, 0.77, 0.9, 0.95, 0.995, 0.95, 0.9,0.8, 0.7, 0.6, 0.5, 0.45, 0.4, 0.35, 0.3, 0.25, 0.2, 0.15, 0.12, 0.1,0.07, 0.05, 0.03, 0.01. Actual points were recorded within an absoluteor relative pressure tolerance of 5 mmHg or 5%, respectively, whicheverwas more stringent. Time between successive pressure readings duringequilibration was 10 seconds.

Determination of the Diameter of an Adsorbent Volume

The diameter of an adsorbent volume, D, is a “circle equivalentdiameter” and is derived from the volume, V, and the vapor path length,L, of the adsorbent volume. The diameter, D, is a circle-equivalentdimension, calculated as (4V/πL)^(1/2). For example, as a genericillustration of the calculation, an adsorbent volume of 200 cc has avapor path length of 10 cm. The diameter is [(4×200)/(10π)]^(1/2)=5.0cm. The L/D is, therefore, 10 cm/5 cm=2.0.

Determination of Flow Restriction

The flow restriction was measured as pressure drop (Pa/cm) for differentshaped adsorbent particles across a 30 mm length of dense-packed bed ata given standard liter per minute (slpm) with the device shown in FIG.4. In particular, the pressure drop (Pa/cm) was measured across a 30 mmdepth at the center of a pellet bed with 43 mm diameter for an air flowrange of 10-70 slpm (11.5-80.3 cm/s). Adsorbent was loaded according toASTM procedure D2854 into a 43 mm inner diameter tube with ports drilled+/−15 mm as measured from the midpoint along the bed length. Open cellfoam was used to contain the carbon bed. For the pressure purge,compressed air was loaded through port 1 to atmosphere on port 2; thepressure drop across ports 3 and 4 was measured. For the vacuum purge, avacuum was pulled through port 1; the pressure drop was measured acrossports 3 and 4. The flow was adjusted from 10-70 slpm (11.5-80.3 cm/s)and pressure drop measured at each adjustment. For monoliths, thepressure drop (Pa/cm) was measured from 10-70 slpm across the entiremonolith. For the 35 mm diameter monolith, the pressure drop at 46 cm/swas approximated from the measurement at 30 lpm flow and, for the 29 mmdiameter monolith, the pressure drop at 46 cm/s was approximated fromthe measurement at 20 lpm flow.

The part flow restriction (such as between ports 1 and 2 in FIG. 4) wasmeasured as pressure drop (kPa) for the part in the housing used forcanister testing. The flow restriction of the part housing was alsomeasured with no adsorbent. The flow was adjusted from 10-70 SLPM(11.5-80.3 cm/s) and pressure drop measured at each adjustment. Thepressure drop in kPa of the adsorbent bed or monolith part was recordedwith correction for the pressure drop of the housing at the same flowrate.

For an adsorbent bed within a canister, the pressure drop of that volumewas calculated by first determining the fundamental Pa/cm vs. cm/s plotfor a 110 mm long bed in a 43 mm internal diameter (ID) auxiliary tubeas described above and illustrated in FIG. 25 and FIG. 30. Then, thecm/s air velocity for 40 lpm was determined from the cross-sectionalarea of the adsorbent volume defined as the ratio of the adsorbentvolume divided by the vapor path length of the adsorbent volume.Finally, the pressure drop in Pa at that cm/s velocity for 40 lpm wascalculated by multiplying the Pa/cm flow restriction property by thevapor path length of the adsorbent volume.

The term “total nominal volume,” as used herein, refers to a sum of thevolumes of the adsorbent components, and does not include the volumes ofgaps, voids, ducts, conduits, tubing, plenum spaces or other volumesalong lengths of the vapor flow path that are devoid of adsorbentmaterial across the plane perpendicular to vapor flow path. For example,in FIG. 1 the total nominal volume of the canister system is the sum ofthe volumes of adsorbent volumes 201, 202, 203, and 204, minus anyvolume that is an empty volume. In FIG. 2, the total nominal volume ofthe canister system is the sum of the volumes of adsorbent volumes 201,202, 203, 204, 301, 302, 303, 304, and 305, minus any volume that is anempty volume.

Determination of Nominal Volume Apparent Density

The term “nominal volume apparent density,” as used herein, is the massof the representative adsorbent in the adsorbent volume divided by thenominal volume of adsorbent, where the length of the volume is definedas the in situ distance within the canister system between theperpendicular plane of the vapor flow path initially in contact with theadsorbent component and the perpendicular plan of the vapor flow pathexiting the adsorbent component.

Non-limiting examples of how to calculate the nominal volume apparentdensity for various forms of adsorbents are described herein.

(A) Granular, Pelletized, or Spherical Adsorbents of Uniform AdsorptiveCapacity Across the Length of the Adsorbent Component Flow Path

The standard method ASTM D 2854 (hereinafter “the Standard Method”) maybe used to determine the nominal volume apparent density of particulateadsorbents, such as granular and pelletized adsorbents of the size andshape typically used for evaporative emission control for fuel systems.The Standard Method may be used to determine the apparent density ofadsorbent volume, when it provides the same apparent density value asthe ratio of the mass and the nominal volume of the adsorbent bed foundin the canister system. The mass of the adsorbent by the Standard Methodis of the representative adsorbent used in the incremental adsorptionanalysis, i.e., equivalently including or excluding inert binders,fillers, and structural components within the adsorbent volume dependingon what representative material is analyzed as the adsorbent sample.

Furthermore, the nominal volume apparent density of adsorbent volume maybe determined using an alternative apparent density method, as definedbelow. The alternative method may be applied to nominal adsorbentvolumes that have apparent densities that are not comparably or suitablymeasured by the Standard Method. Additionally, the alternative apparentdensity method may be applied to particulate adsorbents in lieu of theStandard Method, due to its universal applicability. The alternativemethod may be applied to the adsorbent volume that may containparticulate adsorbents, non-particulate adsorbents, and adsorbents ofany form augmented by spacers, voids, voidage additives within a volumeor sequential similar adsorbent volumes for the effect of net reducedincremental volumetric capacity.

In the alternative apparent density method, the apparent density ofadsorbent volume is obtained by dividing the mass of adsorbent by thevolume of adsorbent, wherein:

(1) the dry mass basis of the representative adsorbent in the adsorbentvolume is measured. For example, a 0.200 g representative sample of the25.0 g total adsorbent mass in an adsorbent volume is measured foradsorptive capacity by the McBain method. Whereas the McBain methodyields an adsorption value of g-butane per g-adsorbent, the applicablemass is 25.0 g for the numerator in the apparent density of theadsorbent volume that then allows conversion of the McBain analyticalvalue to the volumetric property of the adsorbent volume; and

(2) the volume of the adsorbent component in the denominator of theapparent density is defined as the in situ geometric volume under whichthe superficial vapor flow path occurs within the canister system. Thelength of the volume is bounded by a plane perpendicular to thesuperficial vapor flow entrance of the adsorbent volume in question(i.e., the point at which there is adsorbent present on theperpendicular plane) and a plane perpendicular to the superficial flowat the vapor flow exit of the adsorbent volume in question (i.e., thepoint at which there is no adsorbent across the plane perpendicular tovapor flow).

(B) Honeycombs, Monolith, or Foam Adsorbents

(1) Cylindrical Honeycomb Adsorbents

The apparent density of cylindrical honeycomb absorbents may bedetermined according to the procedure of Purification Cellutions, LLC(Waynesboro, Ga.) SOP 500-115. The volume of adsorbent is a multiple ofthe cross-sectional area (A) and the length (h) of the adsorbent. Thelength (h) of the adsorbent is defined as the distance between the frontplane of the adsorbent perpendicular to vapor or gas flow entering theadsorbent and the back plane of the adsorbent where the vapor or gasexits the adsorbent. The volume measurement is that of the nominalvolume, which is also used for defining bed volume ratios for purge. Inthe case of a cylindrical honeycomb adsorbent of circular cross-section,the adsorbent cross-sectional area is determined by πd²/4, where d isthe average diameter measured at four points on each end of thehoneycomb. The nominal adsorbent volume and the nominal volume apparentdensity are calculated as follows:Nominal Adsorbent Volume=h×ANominal Volume Apparent Density=Part Mass/(h×A)

wherein “Part Mass” is the mass of the adsorbent for which arepresentative adsorbent sample was tested for adsorptive properties,including representative proportions of inert or adsorptive binders andfillers.

By way of non-limiting examples, FIG. 5 shows the boundary definitionsfor the nominal volume of a honeycomb adsorbent 109 having across-sectional area A. The vapor or gas flows through the honeycombadsorbent 109 in the direction of D1 to D2. The vapor or gas enters thefront plane (F) of the adsorbent 109, flows through the length (h) ofthe adsorbent 109, and exits back plane (B) of the adsorbent 109. Thenominal volume of a honeycomb adsorbent 109 equals to thecross-sectional area A×the length h. Similarly, FIG. 6 shows theboundary definitions for the nominal volume of foam adsorbent 110.

(2) Pleated, Corrugated and Sheet Adsorbents

For pleated and corrugated adsorbents, the nominal adsorbent volumeincludes all the void space created by the pleats and corrugations. Thevolume measurement is that of the nominal volume, which is also used fordefining bed volume ratios for purge. The nominal volume and theapparent density of adsorbent are calculated as follows:Nominal Adsorbent Volume=h×ANominal Volume Apparent Density=Part Mass/(h×A)

wherein

“Part Mass” is the mass of the adsorbent for which a representativeadsorbent sample was tested for adsorptive properties, includingrepresentative proportions of inert or adsorptive binders and fillers,

h is the length of adsorbent, defined as the distance between the frontplane of the adsorbent perpendicular to vapor or gas flow entering thefilter and the back plane of the adsorbent where the vapor or gas exitsthe filter, and

A is the cross-sectional area of adsorbent.

By way of non-limiting example, FIG. 7 shows the boundary definitionsfor the volume of a stacked corrugated sheet adsorbent monolith 111. Itis also within those skilled in the art to form such a monolith as anextruded honeycomb.

In the case of a pleated adsorbent, the adsorbent cross-sectional areais determined by L×W, where L is the distance from one edge of theadsorbent to the opposite edge of the adsorbent in direction X, and W isthe distance from one edge of the adsorbent to the opposite edge of theadsorbent in direction Y.

By way of non-limiting examples, FIG. 8 shows the boundary definitionsfor the volume of a single pleat or corrugation 112. FIG. 9 shows theboundary definitions for the volume of a pleated or corrugated sheet 113with vapor flow path provided through the sheet by some form ofpermeability to gas flow. The face of the sheet is perpendicular to thevapor flow. In contrast, FIG. 10 shows the boundary definitions for thevolume of a pleated or corrugated sheet 114 where its face is angled togas flow. FIG. 11 shows the boundary definitions for the volume of anadsorbent volume 115 of parallel adsorbent sheets. FIG. 12 shows theboundary definitions for the volume of an adsorbent sleeve 116.

Determination of Incremental Adsorption Capacity

FIG. 13 shows a simplified schematic drawing of the apparatus used forthe determination of the butane adsorption capacity. This is known inthe field as the McBain method. The apparatus 800 includes a sample pan801 and a spring 802 inside a sample tube 803, a rough vacuum pump 804,a diffusion pump 805, a stopcock 806, metal/O-ring vacuum valves807-809, a butane cylinder 810, a pressure readout unit 811, and atleast one conduit 812 connecting the components of the apparatus 800.

The representative adsorbent component sample (“adsorbent sample”) wasoven-dried for more than 3 hours at 110° C. before loading onto thesample pan 801 attached to the spring 802 inside the sample tube 803.Then, the sample tube 803 was installed into the apparatus 800. Theadsorbent sample shall include representative amounts of any inertbinders, fillers and structural components present in the nominal volumeof the adsorbent component when the Apparent Density value determinationequivalently includes the mass of the inert binders, fillers, andstructural components in its mass numerator. Conversely, the adsorbentsample shall exclude these inert binders, fillers, and structuralcomponents when the Apparent Density value equivalently excludes themass of the inert binders, fillers, and structural components in itsnumerator. The universal concept is to accurately define the adsorptiveproperties for butane on a volume basis within the nominal volume.

A vacuum of less than 1 torr was applied to the sample tube, and theadsorbent sample was heated at 105° C. for 1 hour. The mass of theadsorbent sample was then determined by the extension amount of thespring using a cathetometer. After that, the sample tube was immersed ina temperature-controlled water bath at 25° C. Air was pumped out of thesample tube until the pressure inside the sample tube was 10⁻⁴ torr.n-Butane was introduced into the sample tube until equilibrium wasreached at a selected pressure. The tests were performed for two datasets of four selected equilibrium pressures each, taken about 38 torrand taken about 380 torr. The concentration of n-butane was based on theequilibrium pressure inside the sample tube. After each test at theselected equilibrium pressure, the mass of the adsorbent sample wasmeasured based on the extension amount of the spring using cathetometer.The increased mass of the adsorbent sample was the amount of n-butaneadsorbed by the adsorbent sample. The mass of n-butane absorbed (ingram) per the mass of the adsorbent sample (in gram) was determined foreach test at different n-butane equilibrium pressures and plotted in agraph as a function of the concentration of n-butane (in % volume). A 5vol % n-butane concentration (in volume) at one atmosphere is providedby the equilibrium pressure inside the sample tube of 38 torr. A 50 vol% n-butane concentration at one atmosphere is provided by theequilibrium pressure inside the sample tube of 380 torr. Becauseequilibration at precisely 38 torr and 380 torr may not be readilyobtained, the mass of adsorbed n-butane per mass of the adsorbent sampleat 5 vol % n-butane concentration and at 50 vol % n-butane concentrationwere interpolated from the graph using the data points collected aboutthe target 38 and 380 torr pressures.

Alternatively, Micromeritics (such as Micromeritics ASAP 2020) may beused for determining the incremental butane adsorption capacity insteadof the McBain method.

Determination of Nominal Incremental Adsorption Capacity

The term “nominal incremental adsorption capacity,” as used herein,refers to an adsorption capacity according to the following equation:Nominal Incremental Adsorption Capacity=[Adsorbed Butane at 50 vol%−Adsorbed Butane at 5 vol %]×Nominal Volume Apparent Density×1000

wherein

“Adsorbed Butane at 50 vol %” is the gram mass of absorbed n-butane pergram mass of adsorbent sample at 50 vol % butane concentration;

“Adsorbed Butane at 5 vol %” is the gram mass of absorbed n-butane pergram mass of adsorbent sample at 5 vol % butane concentration; and

“Nominal Volume Apparent Density” is as defined herein.

Determination of Butane Working Capacity

The standard method ASTM D5228-16 may be used to determine the butaneworking capacity (BWC) of the adsorbent volumes containing particulategranular and/or pelletized adsorbents. The retentivity (g/dL) iscalculated as the difference between the volumetric butane activity(g/dL) [i.e., the weight-basis saturation butane activity (g/100 g)multiplied by the apparent density (g/cc)] and the BWC (g/dL).

Determination of the Nominal Volume Butane Working Capacity (BWC)

The standard method ASTM D5228 may be used to determine the nominalvolume butane working capacity (BWC) of the adsorbent volumes containingparticulate granular and/or pelletized adsorbents.

A modified version of ASTM D5228 method may be used to determine thenominal volume butane working capacity (BWC) of the particulate,honeycomb, monolith, and/or sheet adsorbent volumes. The modified methodmay also be used for particulate adsorbents, where the particulateadsorbents include fillers, voids, structural components, or additives.Furthermore, the modified method may be used where the particulateadsorbents are not compatible with the standard method ASTM D5228, e.g.,a representative adsorbent sample may not be readily placed as the 16.7mL fill in the sample tube of the test.

The modified version of ASTM D5228 method is as follows. The adsorbentsample is oven-dried for a minimum of eight hours at 110±5° C., and thenplaced in desiccators to cool down. The dry mass of the adsorbent sampleis recorded. The mass of the empty testing assembly is determined beforethe adsorbent sample is assembled into a testing assembly. Then, thetest assembly is installed into the a flow apparatus and loaded withn-butane gas for a minimum of 25 minutes (±0.2 min) at a butane flowrate of 500 ml/min at 25° C. and 1 atm pressure. The test assembly isthen removed from the BWC test apparatus. The mass of the test assemblyis measured and recorded to the nearest 0.001 grams. This n-butaneloading step is repeated for successive 5 minutes flow intervals untilconstant mass is achieved. For example, the total butane load time for a35 mm diameter×150 mm long honeycomb (Example 27 Supplemental CanisterAdsorbent) was 66 minutes. The test assembly may be a holder for ahoneycomb or monolith part, for the cases where the nominal volume maybe removed and tested intact. Alternatively, the nominal volume may needto be a section of the canister system, or a suitable reconstruction ofthe nominal volume with the contents appropriately oriented to the gasflows, as otherwise encountered in the canister system.

The test assembly is reinstalled to the test apparatus and purged with2.00 liter/min air at 25° C. and 1 atm pressure for a set selected purgetime (±0.2 min) according to the formula: Purge Time(min)=(719×NominalVolume (cc))/(2000 (cc/min)).

The direction of the air purge flow in the BWC test is in the samedirection as the purge flow to be applied in the canister system. Afterthe purge step, the test assembly is removed from the BWC testapparatus. The mass of the test assembly is measured and recorded to thenearest 0.001 grams within 15 minutes of test completion.

The nominal volume butane working capacity (BWC) of the adsorbent samplewas determined using the following equation:Nominal Volume BWC (g/dL)=Amount of Butane Purged (g)/Nominal AdsorbentVolume (dL).

whereinAmount of Butane Purged=Mass of the test assembly after loading−Mass ofthe test assembly after purge.

The term “g-total BWC,” as used herein, refers to g-amount of butanepurged.

The term “canister approximate total vapor load,” as used herein, refersthe total weight gain of the canister during 2 day diurnal testing. Itis equal to Day 1 load (g)+Day 2 load (g)−Backpurge (g).

The term “backpurge,” as used herein, refers to the canister weight lossdue to air flow caused by fuel tank vacuum during the Day 1 cool down indiurnal testing.

Determination of Diurnal Breathing Loss (DBL) Emissions

The evaporative emission control systems of Examples 1-118 wereassembled with the selected amounts and types of adsorbents as shown inTables 1-3 (see FIGS. 14-16).

Each example was uniformly preconditioned (aged) by repetitive cyclingof gasoline vapor adsorption using certified TF-1 fuel (9 RVP, 10 vol %ethanol) or EPA certified Tier-3 fuel (9 RVP, 10 vol % ethanol) and 300nominal bed volumes of dry air purge at 22.7 lpm based on the maincanister (e.g., 630 liters for a 2.1 L main canister). The gasolinevapor load rate was 40 g/hr and the hydrocarbon composition was 50 vol%, generated by heating two liters of gasoline to about 36° C. andbubbling air through at 200 mL/min. The two-liter aliquot of fuel wasreplaced automatically with fresh gasoline every two hours until 5000ppm breakthrough was detected by a FID (flame ionization detector). Aminimum of 25 aging cycles were used on a virgin canister. The agingcycles were followed by a single butane adsorption/air purge step. Thisstep was to load butane at 40 g/hour at a 50 vol % concentration in airat one atmosphere to 5000 ppm breakthrough, soak for one hour, thenpurge with dry air for 21 minutes with a total purge volume attained byselecting the appropriate constant air purge rate for that period.During the previous butane load and purge steps occurred within achamber with an atmosphere temperature of approximately 20-25 C. Thecanister was then soaked with the ports sealed for 24 hour at 20° C.

The DBL emissions were subsequently generated by attaching the tank portof the example to a fuel tank filled 40 vol % (based on its ratedvolume) with CARB LEV III fuel (7 RVP, 10 vol. % ethanol) or Phase II (7RVP, 0 vol % ethanol). Prior to attachment, the filled fuel tank hadbeen stabilized at 18.3° C. for 24 hours while venting. The tank and theexample were then temperature-cycled per CARB's two-day temperatureprofile, each day from 18.3° C. to 40.6° C. over 11 hours, then backdown to 18.3° C. over 13 hours. During those two-day cycles for the 68 Ltank and 2.1 L canister described in the current invention, gasolinevapor generation averaged about 34 g for Day 1, back purge averagedabout 8.2 g, and Day 2 vapor generation averaged about 34.3 g for a netvapor challenge of about 61.7 g. In all cases, vapor generation and backpurge were measured by the example canister weight changes during theDay 1 heat-up (Day 1 vapor generation), Day 1 cool-down (back purge),and Day 2 heat-up (Day 2 vapor generation). For fuel systems other thanthe systems described in the current invention, vapor generation andback purge are measured as stated above using the specific or commercialvehicle system fuel tank and canister. Emission samples were collectedfrom the example vent at 6 hours and 12 hours during the heat-up stageinto Kynar bags. The Kynar bags were filled with nitrogen to a knowntotal volume based on pressure and then evacuated into a FID todetermine hydrocarbon concentration. The FID was calibrated with a 5000ppm butane standard. From the Kynar bag volume, the emissionsconcentration, and assuming an ideal gas, the mass of emissions (asbutane) was calculated. For each day, the mass of emissions at 6 hoursand 12 hours were added. Following CARB's protocol the day with thehighest total emissions was reported as “2-day emissions.” In all cases,the highest emissions were on Day 2. This procedure is generallydescribed in SAE Technical Paper 2001-01-0733, titled “Impact andControl of Canister Bleed Emissions,” by R. S. Williams and C. R.Clontz, and in CARB's LEV III BETP procedure (section D.12 in CaliforniaEvaporative Emissions Standards and Test Procedures for 2001 andSubsequent Model Motor Vehicles, Mar. 22, 2012).

For Examples 1-16, a 68 liter fuel tank and a 2.1 liter main canister(Tables 1 and 2, Main Canister Type #1) was used as a main canisterfilled with 2.1 liters of a commercially available activated carbonadsorbent pellet (NUCHAR® BAX 1500 from Ingevity, North Charleston,S.C.). The main canister activated carbon adsorbent pellets aretypically about 2-2.8 mm in length, and have high BWC, low flowrestriction, and low M/m as compared to the vent-side particulateadsorbent materials described herein. The NUCHAR® BAX 1500 activatedcarbon adsorbent was present in two connected volumes of 1.4 and 0.7liters. For Examples 17-25 and 99-100, a 68 liter fuel tank and a 2.1liter main canister (Tables 1 and 2, Main Canister Type #2) was used asa main canister filled with 1.8 liters of NUCHAR® BAX 1500, in twoconnect volumes of 1.4 and 0.4 liters, and 0.3 liters of anothercommercially available activated carbon adsorbent pellet (NUCHAR® BAXLBE from Ingevity, North Charleston, S.C.), as shown in Table 1. Similarto NUCHAR® BAX 1500, NUCHAR® BAX LBE activated carbon adsorbent pelletsare typically about 2-2.8 mm in length, and have high BWC, low flowrestriction, and low M/m as compared to the vent-side particulateadsorbent materials described herein. For Examples 26 and 27, a 68 literfuel tank and a 2.1 liter main canister (Tables 1 and 2, Main CanisterType #3) was used as a main canister filled with 1.8 liter of NUCHAR®BAX 1500, in two connect volumes of 1.4 and 0.4 liters, and 0.3 litersof a commercially available activated carbon adsorbent pellet (MPAC I™from Mahle Corporation) activated carbon adsorbent, as shown in Table 1.For Examples 29-62 and 101-111, a 60 liter fuel tank and a 2.1 litermain canister (Tables 1 and 2, Main Canister Type #4) was used as a maincanister filled with 2.1 liters of a commercially available activatedcarbon adsorbent pellet (NUCHAR® BAX 1100 from Ingevity, NorthCharleston, S.C.) in two connected volumes of 1.4 and 0.7 liters.NUCHAR® BAX 1100 activated carbon adsorbent pellets are typically about2-2.8 mm in length, and have high BWC, low flow restriction, and low M/mas compared to the vent-side particulate adsorbent materials describedherein.

For Examples 63-92, a 60 liter fuel tank and a 2.1 liter main canister(Tables 1 and 2, Main Canister Type #5) was used as a main canisterfilled with 2.1 liters of NUCHAR® BAX 1100 LD (low density) activatedcarbon adsorbent, in two connected volumes of 1.4 and 0.7 liters. ForExamples 93 and 94, a 72.7 liter fuel tank and a 2.875 liter maincanister (Tables 1 and 2, Main Canister Type #6) was used as a maincanister filled with NUCHAR® BAX 1100 activated carbon adsorbent, involumes of 2.7, 0.135, and 0.04 liters. For Example 95, a 72 L fuel tankand a 2.75 liter main canister (Tables 1 and 2, Main Canister Type #7)was used as a main canister filled with 2.3 liters of NUCHAR® BAX 1500,in volumes of 1.8 and 0.5 liters, and 0.45 liters of NUCHAR® BAX 1100activated carbon adsorbent, as shown in Table 1. For Example 96, a 47 Lfuel tank and a 1.8 L main canister (Tables 1 and 2, Main Canister Type#8) was used as a main canister filled with NUCHAR® BAX 1100 activatedcarbon adsorbent. For Example 97-98, a 68 L fuel tank and a 2.1 L maincanister (Tables 1 and 2, Main Canister Type #9) was used as a maincanister filled with 1.8 L NUCHAR® BAX 1500, in two connect volumes of1.4 and 0.4 liters, and 0.3 L of the low retentivity particulateactivated carbon adsorbent material as described herein.

The characteristics of each adsorbent are provided in Tables 1-3 (seeFIGS. 14-16). Where present, the adsorbent volume of a supplementalcanister is described in Table 2. Furthermore, Examples 29-33, 73, 74,94, 96, and 106-111 included an additional adsorbent (described in Table3, see FIG. 15) in the supplement canister that is downstream of thefirst adsorbent of the supplemental canister described in Table 1.

The adsorbent volume fills and dimensions for several of the exemplarymain canisters described in Table 1 are provided below. The adsorbentvolumes 201, 202, 203, and 204 refer to the volumes shown in FIG. 1. Thedesignation “201+202” refers to a single adsorbent volume encompassingthe right side of the canister in the FIG. 1 illustration. Thedesignation “203+204” refers to a single adsorbent volume encompassingthe left side of the canister in the FIG. 1 illustration.

For Canister Type #1

The 201+202 volume is 1400 cc of NUCHAR® BAX 1500 and vapor flow pathlength of 201+202 volume is 16.7 cm. The average cross-sectional area is84 cm2, the circle equivalent diameter is 10.3 cm, and the L/D is 1.6.

The 203+204 volume is 700 cc of NUCHAR® BAX 1500 and the vapor flow pathlength of 203+204 is 16.6 cm. The average cross-sectional area is 45cm2, the circle equivalent diameter is 7.6 cm, and the L/D is 2.1.

For Canister Type #2

The 201+202 volume is 1400 cc of NUCHAR® BAX 1500 and vapor flow pathlength of 201+202 volume is 16.7 cm. The average cross-sectional area is84 cm2, the circle equivalent diameter is 10.3 cm, and the L/D is 1.6.

The 203 volume is 400 cc of NUCHAR® BAX 1500 and the vapor flow pathlength of 203 volume is 7.8 cm. The average cross-sectional area is 51cm2, the circle equivalent diameter is 8.1 cm, and the L/D is 1.0.

The 204 volume is 300 cc of NUCHAR® BAX LBE and the vapor flow pathlength is 7.8 cm. The average cross-sectional area is 38 cm2, the circleequivalent diameter is 7.0 cm, and the L/D is 1.1.

For Canister Type #3

The 201+202 volume is 1400 cc of NUCHAR® BAX 1500 and vapor flow pathlength of 201+202 volume is 16.7 cm. The average cross-sectional area is84 cm2, the circle equivalent diameter is 10.3 cm, and the L/D is 1.6.

The 203 volume is 400 cc of NUCHAR® BAX 1500 and the vapor flow pathlength of 203 volume is 7.8 cm. The average cross-sectional area is 51cm2, the circle equivalent diameter is 8.1 cm, and the L/D is 1.0.

The 204 volume is 300 cc MPAC 1™ and the vapor flow path length is 7.8cm. The average cross-sectional area is 38 cm2, the circle equivalentdiameter is 7.0 cm, and the L/D is 1.1.

For Canister Type #4

The 201+202 volume is 1400 cc of NUCHAR® BAX 1100 and vapor flow pathlength of 201+202 volume is 16.7 cm. The average cross-sectional area is84 cm2, the circle equivalent diameter is 10.3 cm, and the L/D is 1.6.

The 203+204 volume is 700 cc of NUCHAR® BAX 1100 and the vapor flow pathlength of 203+204 is 16.6 cm. The average cross-sectional area is 45cm2, the circle equivalent diameter is 7.6 cm, and the L/D is 2.1.

For Canister Type #5

The 201+202 volume is 1400 cc of NUCHAR® BAX 1100 LD and vapor flow pathlength of 201+202 volume is 16.7 cm. The average cross-sectional area is84 cm2, the circle equivalent diameter is 10.3 cm, and the L/D is 1.6.

The 203+204 volume is 700 cc of NUCHAR® BAX 1100 LD and the vapor flowpath length of 203+204 is 16.6 cm. The average cross-sectional area is45 cm2, the circle equivalent diameter is 7.6 cm, and the L/D is 2.1.

For Canister Type #9

The 201+202 volume is 1400 cc of NUCHAR® BAX 1500 and vapor flow pathlength of 201+202 volume is 16.7 cm. The average cross-sectional area is84 cm2, the circle equivalent diameter is 10.3 cm, and the L/D is 1.6.

The 203 volume is 400 cc of NUCHAR® BAX 1500 and the vapor flow pathlength of 203 volume is 7.8 cm. The average cross-sectional area is 51cm2, the circle equivalent diameter is 8.1 cm, and the L/D is 1.0.

The 204 volume is 300 cc of the inventive low flow restriction pelletsalso found in example 101, and the vapor flow path length is 7.8 cm. Theaverage cross-sectional area is 38 cm2, the circle equivalent diameteris 7.0 cm, and the L/D is 1.1.

Tables 1-3 summarize the conditions of the canister systems of Examples1-111 and their measured 2-day DBL emissions. As discussed above, theCalifornia Bleed Emissions Test Procedure (BETP) requires that a 2-dayDBL emissions of less than 20 mg. As will be described in the followingparagraphs, the requirement not to exceed 20 mg for BETP under purge ator below 150 BV was met by the evaporative emission control canistersystems of the present disclosure.

As can be seen in the data provided in Table 2, and as will be discussedbelow, evaporative emission control canister systems of the presentdisclosure have low two-day DBL, e.g., below about 50 mg or below about20 mg. The adsorbent volumes in the examples are described via the fuelvapor flow path, i.e., in order from the fuel vapor inlet to the ventport. It should be understood that the illustrations and description ofadsorbent volumes as “fuel-side” and “vent-side” are provided forcertain aspects and embodiments and, as would be appreciated by theskilled artisan, are not limiting on the scope of the presentdisclosure. It is expressly contemplated that the described lowretentivity particulate adsorbent volume(s), can be located at anynumber of positions in the flow path from fuel inlet (104 in FIG. 2) tovent port (105 in FIG. 2). Indeed, one or more of the described lowretentivity particulate adsorbent volume(s) can be placed upstreamand/or downstream of (i) one or more high working capacity adsorbentvolumes, (ii) one or more of another low capacity adsorbent volume,e.g., a monolith, honeycomb, polymer or paper sheet, or (iii) anycombination thereof.

For example, with reference to FIG. 2, in certain examples the fuel-sideadsorbent volume 201 is the first adsorbent volume in the flow path fromfuel vapor inlet 104 to the vent port 105. In such an instance, eachadditional adsorbent volume in the vapor flow path (i.e., 202, 203, 204,301, 302, 303, 304, and 305) can be considered a vent-side adsorbentvolume. In certain embodiments, the first adsorbent volume comprises ahigh working capacity adsorbent material, such as a particulate.However, the system is not so limited. For example, also contemplatedare canister systems in which the high working capacity adsorbentmaterial is downstream of a first volume or is comprised in a pluralityof adsorbent volumes along the flow path. In certain embodiments, thehigh working capacity adsorbent volume is upstream, downstream or bothof a lower working capacity adsorbent volume such as the particulateadsorbent volume as described herein, a monolith, a honeycomb, a polymeror paper sheet or combination thereof. Moreover, as will be recognizedby the skilled artisan, the respective adsorbent volumes as describedherein can be located in the same canister or separate canisters orboth, and the particular configuration of FIG. 2 is not limiting on thedescribed canister systems. Furthermore, any number of the adsorbentvolumes can include a voidage between them.

Example systems 32 and 33 utilize main canister 4, which includesNUCHAR® BAX 1100 LD at the fuel vapor side of the system. Thesupplemental canister of Example 32 includes MPAC I followed by 29×100activated carbon honeycomb (HCA) (Ingevity®, Charleston, S.C., USA),while the supplemental canister of Example 33 includes a low retentivityparticulate adsorbent as described herein followed by 29×100 HCA. As canbe seen from Table 2, Example 33 has a substantially lower two-day DBL(31.1 mg), as compared to comparative Example 32 (50.9 mg). Similarly,Example 31 (NUCHAR® BAX1100, low retentivity particulate adsorbent,29×100 HCA) had a substantial decrease (17.1 mg) relative to Example 29(44.6 mg; NUCHAR® BAX 1100, 5 mm NUCHAR® BAX LBE, 29×100 HCA).

Furthermore, low retentivity particulate adsorbent containing Examples43, 52, 53, 57, 58, 59, 60, and 62 also demonstrated a two-day DBL below20 mg. Similar to Example 35, NUCHAR® BAX 1100 is located on the fuelvapor side in the main canister and low retentivity particulateadsorbent is present downstream (i.e., toward the vent port). Ascompared to comparative examples (e.g. Examples 64, 65, 66, 67, 89, 90,91, and 68) that received similar purge treatment (i.e., purge BV of 150and a purge of 315 L), these examples have substantially lower two-dayDBL, which are below the California BETP required 20 mg. Examples thatinclude main canister 5 (NUCHAR® BAX 1100 LD fuel vapor side) and asupplemental canister having a low retentivity particulate adsorbent(e.g., Examples 80, 85, 79, 88, 86, and 87) also had a two-day DBL below20 mg.

FIGS. 17-20 demonstrate that the capacity vs. path length function ofthe first adsorbent of the supplemental canister in Example 31 (i.e., alow retentivity adsorbent as described herein) is non-monotonic. Thatis, it is surprising and unexpectedly observed that at a certain pathlength, the adsorbent has an unexpected increase in capacity.

FIG. 21 illustrates with examples the well-known performance tradeoffwith conventional solid particulate adsorbents (cylindrically shapedpellets, “filled diamonds”) with diameters of 2-5 mm in providing thetarget flexibility of reasonable flow restriction and DBL emissionsperformance. These examples are for main canisters with one or morevent-side adsorbent volumes with alternative adsorbent fills, asdescribed in Tables 2 and 3. When tested under a BETP protocol employinga purge applied after the 40 g/hr butane loading step of less than 150bed volumes (BV) based on the total nominal volume of adsorbents in thesystem (see conventional examples in Tables 1-3 for the systemdescriptions), only the carbon honeycomb examples populate the space ofa reasonable flow restriction for a vent-side volume of <0.3 kPa at 40standard liter per minute (slpm) for the chamber (i.e., the chambercontaining the adsorbent volume, less the empty holder) and with a BETPtest result of less than 50 mg for day 2 DBL emissions. In contrast, theconventional pellets smaller than 3 mm, though a low cost solution, havean unfortunate tradeoff between flow restriction and emissionsperformance. These pellets might match the emissions performance butrequires geometric proportions of the adsorbent bed (e.g., low bedlength relative to diameter, that imposes excessive flow restriction, ora reasonable flow restriction is provided by a more favorable bedproportions but the DBL emissions are excessive. As noted in above forapplying low cross sectional area to adsorbent volume or chamberdimensions according to the teaching of U.S. Pat. No. 5,957,114, theelongated chamber with a length to diameter ratio, L/D, of greater than2 favor the low DBL emissions response (FIG. 22) for the conventionalparticulate adsorbents in comparison with the carbon honeycombadsorbents of similar dimensions, but those conventional adsorbents haveexcessive flow restriction (FIG. 23). Notably, the large diameter solidpellet (Example 1) overcomes the flow restriction barrier for thefavorable chamber geometry of an L/D greater than 2, but the DBLemissions performance of the system is severely impaired, attributed tothe poor purgeability of the large diameter solid pellets.

FIGS. 24 and 25 illustrate the flow restriction of the conventionalpellets and carbon honeycombs for the flow rates often cited forevaporative emission control canister systems. As described above, acanister system manufacturer might initially design an overall adsorbentchamber strategy, and then go about comparing available products, incomparing and balancing the factors of cost, flow restriction, workingcapacity performance and bleed control, among others. For thecomparisons in FIGS. 24 and 25, the 43 mm diameter×150 mm long(“43×150”) particulate adsorbent bed is a representative example of thevolume fill of a chamber with particulate adsorbent that would otherwisecontain a 35 mm diameter×150 mm long carbon honeycomb (“35×150”), thatis the 35 mm diameter carbon honeycomb plus a 4 mm thick o-ring. Ano-ring, or other sealant material, both keeps the honeycomb in-place andseals between the honeycomb exterior skin and the chamber interior wall,causing air and vapor flows to go through the honeycomb cells and notbypass in the peripheral gap around the monolith. In FIG. 24, typicallyfamiliar flows encountered in canister system testing and qualificationare highlighted. The 15 slpm is the purge flow employed in a 150 BV DBLprep for a 2.1 liter canister system. A purge rate of 22.7 slpm istypically used in EPA GWC and GWC measurements. The maximum fuel flowfor ORVR in the US is about 10 gallons per minute, meaning a displacedair-vapor flow to the canister system of about 40 slpm. A canistersystem specification by GM for maximum flow restriction under ORVR, ascited in the Background, is at 60 slpm. FIG. 25 shows those importantflows in terms of the gas velocities for the vent-side volumes in FIG.21 through 23, and the flow restriction, not in terms of chamberrestriction, but in terms of the flow restriction per length of bed orpart for a 43 mm diameter bed for the particulate examples, as a meansfor comparing flow restriction properties of materials. Clearly, theconventional solid pellets of the typical 2-2.8 mm diameter as foundwithin main canister chambers are not competitive with carbonhoneycombs, making their potentially low emissions performanceimpractical for the required chamber geometries of an L/D greater than2.

To address the limitations exhibited by conventional pellet media forvent-side fills the description provides a particulate adsorbent in atleast one volume within the canister system that: 1) employs particulateshapes of sufficiently large size, e.g., nominal diameter, so as toobtain low flow restriction properties (Pa/cm pressure drop) and therebytemper the flow restriction of chambers with favorably elongatedgeometries, 2) avoids solid forms such as solid cylinders so as toenhance DBL emissions performance, and 3) employs adsorbent materialsprepared with appropriate choice of fillers, binders, and extrusion aidsso as to obtain an M/m ratio in a range of 150+% for low retentivity,which is contrary to conventional wisdom, and obtain low flowrestriction vent-side particulate adsorbents. Thus, the descriptionsurprisingly and unexpectedly provides a canister system including avent-side particulate adsorbent volume with 150+ M/m properties, andwith <40 Pa/cm pressure drop flow restriction properties under 46 cm/sapparent linear air flow velocity when measured as a 43 mm diameter bed.

U.S. Pat. No. 9,174,195, for example, teaches away from making a lowflow-restriction adsorbent particulate material that provides superiorDBL emissions control, good strength, and low retentivity properties. Assuch, the present findings are surprising and unexpected. In addition,the 2.6 mm diameter (as measured by calipers) conventional solidactivated carbon pellet, 2GK-C7 (Kuraray Chemical Co., Ltd.) asdescribed in U.S. Patent application 2007/78056A1 also teaches that suchperformance cannot be obtained from a larger pellet that limits flowrestriction.

2GK-C7 may be found in canister systems installed in 2010 model yearMitsubishi Outlander™ “PZEV” and “federal” vehicles (i.e., thosecertified via EPA Tier 2, meeting a 500 mg/day 2-day full vehicle testrequirement), and in 2010 model year Suzuki SX-4 vehicles. As obtainedin 2010 from canister systems made for such vehicles, the 2GK-C7 has apellet diameter of about 2.7 mm, has an M/m property of 164%, and aretentivity of about 0.6 g/dL as determined using the methods asdescribed herein. The 2GK-C7 pellet has a strength of 99+ by thecommercially accepted method employed here. The '195 patent teachesthat, in preparing a large diameter pellet with M/m increased to levelsgreater than 150%, there is an asymptotic leveling off of retentivity toabout 1 g/dL and a sharp decrease in strength (FIGS. 5 and 6,respectively of the '195 patent), thereby restricting large diameterpellets with suitable strength and adsorptive properties to a spacedefined by an M/m of less than 150%, and preferably in the range of65-150%.

In certain embodiments, present description provides evaporativeemission canister systems comprising at least one vent-side particulateadsorbent volume, wherein the particulate adsorbent material has an M/mof greater than 200%, and <1 g/dL butane retentivity. In anotherembodiment, the particulate adsorbent material has an M/m of above 150%,and <0.5 g/dL butane retentivity. Inventive examples for theseembodiments are described herein.

The use of Pa/cm flow restriction as measured by the protocol definedherein is more appropriate than pellet diameter because complicatedgeometric shapes could preclude accurate measurement of a characteristicdiameter as otherwise easily assigned for circular cross-sectionscylinders, triangular solids, square solid, pentagonal solids, hexagonalsolids, etc. For purposes of physical examples of the invention, ahollow solid-walled cylinder has been employed herein. Yet, alternativeshapes for low flow restriction with hollow characteristics (e.g., thinwalls and low diffusional path length resistance between the bulk phaseand the adsorbent interior) may be utilized, and these shapes includetwisted ribbons, coiled strands, saddles, or hollow shells. These shapesmay further include striations, indentations, and perforations forimparting better strength and adsorbate purgeability properties.Furthermore, these more complex shapes may enable a smaller apparentgeometric “diameter” that could accommodate lower flow restriction thana simple cylinder or geometric solid of similar diameter might otherwiseaccommodate, e.g., an open spring, twisted ribbon, or saddle comparedwith a particulate formed as solid walled cylinder with axially orientedparallel channels.

In contrast with the conventional particulate adsorbent examples in FIG.21, FIG. 26 shows examples of particulate adsorbent having the featuresas described herein capable of providing low DBL emissions and low flowrestriction performance was not possible with the conventional materialsas exemplified in FIG. 21. Certain configurations of carbon honeycombsas well as the materials as described herein (“the inventive examples”)do not fill the performance box. Numerous inventive examples do fill theperformance box with lower DBL emissions than exhibited by the carbonhoneycombs, with chamber flow restrictions approaching that of thecarbon honeycombs. While all of these high performing examplescharacteristically have M/m properties greater than 150%, many have M/mproperties greater than 200%.

FIG. 27 illustrates high performing inventive examples with favorablyhigh chamber L/D of greater than 2 which is considered to be acontributing factor for the low DBL emissions. FIGS. 28, 29, and 30 andshow how the feasibility of low flow restriction for the favorably highL/D is made possible by the low flow restriction properties of theinventive examples. At 46 cm/s apparent linear air flow velocity, theinventive examples are a bare fraction of the Pa/cm pressure drop flowrestriction of the conventional 2-2.8 mm diameter solid conventionalpellets when placed in similar 43 mm diameter chambers.

A further surprising aspect of the present invention is the goodstrength properties of the inventive samples at M/m ratio of ≥150%,despite the teachings of prior art, particularly U.S. Pat. No.9,174,195. FIG. 42 shows the pellet strength of the particulateadsorbent in the examples of FIGS. 26 and 27 as a function of the M/mproperties, where “LFR” indicates low flow restriction. For comparisonpurposes, one metric of acceptable strength is 35 by this test. A 35strength is the property measured for MPAC1 (Kuraray Chemical Co., Ltd.;shown as a solid triangle symbol in FIG. 42) that was obtained fromcanister systems manufactured for evaporative emissions control invehicles. MPAC1 is hollow, cylindrical, low flow restriction pellet withgeometry and properties that fall within the ranges taught by U.S. Pat.No. 9,174,195 pellet, including an M/m of 66%, and was found as anadsorbent fill within a vent-side volume in commercial canister systems.A second industry accepted metric for comparison purposes is the minimumproduct strength specification of 40 that is required by some canistersystem manufacturers for the high working capacity 2 mm Nuchar® BAX 1700activated carbon pellets. As apparent from FIG. 42, the inventiveexamples have strengths well above the commercially typical value of 35for a low flow restriction pellet and well above the 40 minimumspecification of a high working capacity pellet. As shown in FIG. 43 forthe set of inventive canister system examples of FIGS. 26 and 27, theinventive low flow restriction particulate adsorbents are able toachieve excellent control of DBL emissions while demonstrating goodpellet strength, and with (or despite) their high M/m properties. Whilea couple of the inventive low flow restriction particulate adsorbents inthe canister system examples have pellet strength at, or just below, thecomparative 35 and 40 strength metrics, the strength of the samples canbe further optimized by, for example, modifying the binder formulationbut maintaining the other desired characteristics according to thepresent disclosure.

The versatility of the inventive examples is shown by their performanceunder the especially challenging conditions of low purge. For example,U.S. Pat. No. 9,732,649 teaches that control of DBL emissions to verylow levels under low purge conditions of less than 100 BV applied afterthe 40 g/hr butane loading step, or of less than 210 liters purge, canbe difficult as tested under BETP test protocol. Under those challengesof low purge, FIG. 31 shows the examples from FIG. 26 filtered for theexamples where that <100 BV and <210 liter level of purge was appliedafter the 40 g/hr butane loading step, where all examples in FIGS. 26and 31 had only one vent-side adsorbent volume external to the maincanister. FIG. 32 shows that when an additional vent-side particulatewas added in a bed (“Adsorbent 2”), low system emissions with the lowflow restriction is observed. As shown in FIGS. 33 and 34, the inventiveparticulates were contained as a bed in an Adsorbent 2 chamber with L/Dproportions similar to those of the carbon honeycombs. The shift to alower L/D value reflects the lack of a space-consuming andcross-sectional area-limiting sealing and retaining o-ring, or similarsealant that is otherwise required for a carbon honeycomb.Significantly, the inventive particulate bed of Adsorbent 2 in examples107-110 that resulted in the low emissions of these canister systemsunder low purge conditions had pellet strength of 51 even with its highM/m ratio of 260%.

For this type 4 main canister the very low DBL emissions under low purgeconditions was obtained for combinations of an inventive pelletadsorbent in combination with a particular 35×100 carbon honeycomb insubsequent adsorbent volumes. With the 35×100 carbon honeycomb as thefinal adsorbent volume towards the system vent (canister system inexample 106), the day 2 DBL emissions were 15 mg. However, with theinventive pellets filling that final chamber containing as a 43×100Adsorbent 2 (canister system in example 107), the day 2 DBL emissionswere even lower, at 12 mg. This result is surprising becauseconventional wisdom suggested the benefits of a monotonically declininggradation in working capacity towards the system atmosphere vent as mostbeneficial to DBL emissions especially for attaining <20 mg under a lowpurge condition. The present disclosure provides new options with avent-side particulate adsorbent fill to achieve that result, including,e.g., with only one adsorbent volume in the canister system containing acarbon honeycomb rather than in multiple volumes with flexibility ofwhere that particulate volume may be placed, with particulate porosityproperties that had been taught against yet are now shown to be ofsuperior DBL emission performance. The implication and opportunity forcanister system design, for example, is the advantage of being able totake an existing canister system, designed with multiple in-seriesadsorbent volumes accommodating carbon honeycombs at the vent-side, and,having the flexibility to opt for a vent-side particulate adsorbentsolution in one or more of these volumes without having to redesign andretool the system, and still getting the desired DBL emissionsperformance outcome within total system pressure drop constraints.

In certain embodiments, the description provides emission controlcanister systems including a vent-side particulate adsorbent with theM/m greater than 150%, and a butane retentivity property of <0.5 g/dLwhere low DBL emissions result, accompanied by moderate flow restrictionof the vent-side adsorbent volume. For example, a type 4 main canister(2.1 L carbon fill) was outfitted fitted on its vent-side with a chambercontaining a 43 mm diameter by 100 mm long adsorbent bed of low flowrestriction hollow pellet particulates, and the system was cycled with a315 L purge applied after the 40 g/hr butane loading step, or a 139 BVpurge for that total adsorbent volume (see examples 36-62). The 2 dayDBL emissions for the base canister was 76 mg (e.g., example 28; themain canister tested without the 43×100 external vent-side chamber, sothe 315 L purge was 150 BV for that 2.1 L of total adsorbent bed). TheL/D ratio of the adsorbent volume in the auxiliary chamber located onthe canister vent-side was 2.56. The flow restriction of the pellet bedin that chamber was 0.22 kPa at 40 lpm flow (10.0 Pa/cm at 46 cm/sapparent linear air flow velocity), except for the higher, 0.26 kPa(13.3 Pa/cm flow restriction property at 46 cm/s apparent linear airflow velocity) for the Kuraray MPAC1 prior art pellet in example 47. Asshown in FIGS. 35 and 36, this canister system has multiple inventiveexamples with M/m of 150+% that have emissions of <20 mg, and someexamples at <10 mg when the butane retentivity property of the low flowrestriction pellets was <0.5 g/dL. FIG. 44 illustrates the pelletstrengths for inventive low flow restriction particulate adsorbents inthe examples of FIGS. 35 and 36. The inventive low flow restrictionparticulates of M/m of 150+%, including M/m properties that are wellabove 200+%, and of butane retentivity properties below 0.5 g/dL, havepellet strengths at, and frequently well above, 35.

Another embodiment is shown with a type 5 main canister (2.1 L carbonfill) which was outfitted fitted on its vent-side with an Adsorbent 1auxiliary chamber. The 2 day DBL emissions for the base canister was 93mg (e.g., example 63; the main canister tested without the auxiliaryAdsorbent 1 chamber, so the 315 L purge was 150 BV for that 2.1 L oftotal adsorbent bed). The auxiliary chamber consisted of various sizeAdsorbent 1 beds of conventional pellets, low flow restriction hollowpellet particulates, or carbon honeycombs. The canister system wascycled with a 315 L purge applied after the 40 g/hr butane loading step,or a 137-147 BV purge for the total nominal adsorbent volumes. Allexamples were purged with the same 315 L, but the BV value depended onthe size of the vent-side chamber external to the main canister whichvaried among the examples (see examples 64-69, 76, 79, and 88-92).Similar to the examples in FIGS. 35 and 36, FIGS. 37 and 38 show, of thetested adsorbents that include both particulate and honeycomb forms, thelowest emissions was by a flow restriction particulate adsorbent with anM/m property of greater than 150% and butane retentivity of less than0.5 g/dL. This material was tested in replicate (examples 86 and 87),because of its surprising low bleed emission performance relative to theother tested particulate and honeycomb materials tested in the Adsorbent1 volumes. The low flow restriction properties for that low flowrestriction particulate (10 Pa/cm at 46 cm/s apparent linear air flowvelocity in FIG. 39), enabled a reasonably low flow restriction of theAdsorbent 1 bed (0.72 kPa at 40 lpm in FIG. 40) with dimensions of 43 mmdiameter with 132 mm length, therefore enabling a favorable bed L/D ofjust over 3 (see FIG. 41) that contributed to the enhanced bleedemissions control.

Exemplary Embodiments

In an aspect, the disclosure provides an evaporative emission controlcanister system comprising one or more canisters having a plurality ofchambers, each chamber defining a volume, which are in fluidcommunication allowing a fluid or vapor to flow directionally from onechamber to the next, and at least one chamber comprises at least oneparticulate adsorbent volume, wherein the at least one particulateadsorbent volume includes a particulate adsorbent having microscopicpores with a diameter of less than about 100 nm, macroscopic poreshaving a diameter of about 100-100,000 nm, and a ratio of a volume ofthe macroscopic pores to a volume of the microscopic pores that isgreater than about 150%, and wherein the particulate adsorbent volumehas a flow restriction property of less than 40 Pa/cm under conditionsof 46 cm/s apparent linear air flow velocity applied to a 43 mm diameterbed of the particulate adsorbent material.

In an additional aspect, the disclosure provides an evaporative emissioncontrol canister system including one or more canisters comprising atleast one fuel-side adsorbent volume; and at least one vent-sideparticulate adsorbent volume comprising a particulate adsorbent havingmicroscopic pores with a diameter of less than about 100 nm, macroscopicpores having a diameter of about 100-100,000 nm, and a ratio of a volumeof the macroscopic pores to a volume of the microscopic pores that isgreater than about 150%, wherein the vent-side adsorbent volume has aflow restriction property of less than 40 Pa/cm pressure drop when a 46cm/s apparent linear air flow velocity is applied to a 43 mm diameterbed of the vent-side particulate adsorbent volume.

In a further aspect, the disclosure provides an evaporative emissioncontrol canister system including one or more canisters comprising atleast one fuel-side adsorbent volume; and at least one vent-side lowretentivity particulate adsorbent volume comprising a particulateadsorbent having microscopic pores with a diameter of less than about100 nm, macroscopic pores having a diameter of about 100-100,000 nm, anda ratio of a volume of the macroscopic pores to a volume of themicroscopic pores that is greater than about 150%, wherein the at leastone vent-side low retentivity particulate adsorbent volume has a butaneretentivity of less than 0.5 g/dL.

In an additional aspect, the disclosure provides an evaporative emissioncontrol canister system including one or more canisters comprising atleast one fuel-side adsorbent volume; and at least one vent-side lowretentivity particulate adsorbent volume comprising a particulateadsorbent having microscopic pores with a diameter of less than about100 nm, macroscopic pores having a diameter of about 100-100,000 nm, aratio of a volume of the macroscopic pores to a volume of themicroscopic pores that is greater than about 200%, and wherein the atleast one vent-side particulate adsorbent volume has a butaneretentivity of less than 1 g/dL.

In another aspect, the disclosure provides an evaporative emissioncontrol canister system comprising a fuel tank for storing fuel; anengine having an air induction system and adapted to consume the fuel;an evaporative emission control canister system including one or morecanisters comprising a plurality of adsorbent volumes including at leastone fuel-side adsorbent volume; and at least one vent-side particulateadsorbent volume comprising a particulate adsorbent having microscopicpores with a diameter of less than about 100 nm, macroscopic poreshaving a diameter of about 100-100,000 nm, a ratio of a volume of themacroscopic pores to a volume of the microscopic pores that is greaterthan about 150%, and a retentivity of about 0.5 g/dL or less; a fuelvapor inlet conduit connecting the evaporative emission control canistersystem to the fuel tank; a fuel vapor purge conduit connecting theevaporative emission control canister system to the air induction systemof the engine; and a vent port for venting the evaporative emissioncontrol canister system and for admission of purge air to theevaporative emission control canister system, wherein the evaporativeemission control canister system is defined by: a fuel vapor flow pathfrom the fuel vapor inlet conduit through a plurality of adsorbents tothe vent port, and an air flow path from the vent port through theplurality of adsorbent volumes and the fuel vapor purge outlet.

In an additional aspect, the disclosure provides methods for reducingfuel vapor emissions in an evaporative emission control system, themethod comprising contacting the fuel vapor with a plurality ofadsorbent volumes including at least one fuel-side adsorbent volume; andat least one vent-side particulate adsorbent volume comprising aparticulate adsorbent having microscopic pores with a diameter of lessthan about 100 nm, macroscopic pores having a diameter of about 100 nmor greater, a ratio of a volume of the macroscopic pores to a volume ofthe microscopic pores that is greater than about 150%, and a retentivityof about 1.0 g/dL or less.

In further aspects, the disclosure provides, an evaporative emissioncontrol canister system including one or more canisters comprising atleast one fuel-side adsorbent volume comprising a particulate adsorbenthaving microscopic pores with a diameter of less than about 100 nm,macroscopic pores having a diameter of about 100-100,000 nm, a ratio ofa volume of the macroscopic pores to a volume of the microscopic poresthat is greater than about 150%, and a retentivity of less than about1.0 g/dL; and at least one vent-side particulate adsorbent volumecomprising a particulate adsorbent having microscopic pores with adiameter of less than about 100 nm, macroscopic pores having a diameterof about 100-100,000 nm, a ratio of a volume of the macroscopic pores toa volume of the microscopic pores that is greater than about 150%,wherein the at least one vent-side particulate adsorbent volume has abutane retentivity of less than 1.0 g/dL.

In any of the aspects or embodiments described herein, the at least oneparticulate adsorbent volume, at least one vent-side particulateadsorbent volume or at least one vent-side low retentivity particulatevolume has at least one of: a flow restriction of less than 0.3 kPaunder 40 lpm air flow, a flow restriction property of less than 40 Pa/cmpressure drop when a 46 cm/s apparent linear air flow velocity isapplied to a 43 mm diameter bed, a length to diameter ratio of 2 ormore, or a combination thereof.

In any of the aspects or embodiments described herein, the at least oneparticulate adsorbent volume, at least one vent-side particulateadsorbent volume or at least one vent-side low retentivity particulatevolume has at least one of: (i) a retentivity of less than 1.0 g/dL,(ii) a ratio of a volume of the macroscopic pores to a volume of themicroscopic pores that is greater than about 200%, (iii) a length todiameter ratio of 2 or more or (iv) a combination thereof.

In any of the aspects or embodiments described herein, the evaporativeemission control canister system has two-day diurnal breathing loss(DBL) of no more than 50 mg at no more than 315 liters of purge appliedafter a 40 g/hr butane loading step as determined by the 2012 CaliforniaBleed Emissions Test Procedure (BETP).

In any of the aspects or embodiments described herein, the evaporativeemission control canister system has two-day diurnal breathing loss(DBL) of no more than 20 mg at no more than 210 liters of purge appliedafter a 40 g/hr butane loading step as determined by the 2012 CaliforniaBleed Emissions Test Procedure (BETP).

In any of the aspects or embodiments described herein, the evaporativeemission control canister system has two-day diurnal breathing loss(DBL) of no more than 50 mg at no more than 150 bed volumes of purgeapplied after a 40 g/hr butane loading step as determined by the 2012California Bleed Emissions Test Procedure (BETP).

In any of the aspects or embodiments described herein, the evaporativeemission control canister system has two-day diurnal breathing loss(DBL) of no more than 20 mg at no more than 100 bed volumes of purgeapplied after a 40 g/hr butane loading step as determined by the 2012California Bleed Emissions Test Procedure (BETP).

In any of the aspects or embodiments described herein, the evaporativeemission control canister system comprises at least one fuel-sideadsorbent volume, at least one vent-side adsorbent volume or both.

In any of the aspects or embodiments described herein, the adsorbentvolumes are located within a single canister or within a plurality ofcanisters that are connected to permit sequential contact by the fuelvapor.

In any of the aspects or embodiments described herein, the at least oneparticulate adsorbent volume, at least one vent-side particulateadsorbent volume or at least one vent-side low retentivity particulatevolume, the at least one vent-side subsequent adsorbent volume or acombination thereof has a nominal BWC of less than 8 g/dL, a nominal IACat 25 C of less than 35 g/L between vapor concentrations of 5 vol % and50 vol % n-butane, or both.

In any of the aspects or embodiments described herein, the at least onevent-side subsequent adsorbent volume is an activated carbon honeycomb.

In any of the aspects or embodiments described herein, the at least oneparticulate adsorbent volume, at least one vent-side particulateadsorbent volume or at least one vent-side low retentivity particulatevolume, has a retentivity of less than 0.5 g/dL.

In any of the aspects or embodiments described herein, the fuel-sideadsorbent volume has a nominal butane working capacity of at least 8g/dL (e.g., at least 10 g/L), a nominal incremental adsorption capacity(IAC) at 25° C. of at least 35 g/L between vapor concentrations of 5 vol% and 50 vol % n-butane, or both

In any of the aspects or embodiments described herein, the at least onefuel-side adsorbent volume, the at least one particulate adsorbentvolume, at least one vent-side particulate adsorbent volume or at leastone vent-side low retentivity particulate volume, the at least onevent-side subsequent adsorbent volume, or a combination thereof includesan adsorbent material selected from the group consisting of activatedcarbon, carbon charcoal, zeolites, clays, porous polymers, porousalumina, porous silica, molecular sieves, ball clay, kaolin, titania,ceria, and combinations thereof.

In any of the aspects or embodiments described herein, the at least onevent-side subsequent adsorbent volume is an activated carbon honeycomb.

In any of the aspects or embodiments described herein, the activatedcarbon is derived from a material including a member selected from thegroup consisting of wood, wood dust, wood flour, cotton linters, peat,coal, coconut, lignite, carbohydrates, petroleum pitch, petroleum coke,coal tar pitch, fruit pits, fruit stones, nut shells, nut pits, sawdust,palm, vegetables, synthetic polymer, natural polymer, lignocellulosicmaterial, and combinations thereof.

In any of the aspects or embodiments described herein, the form of theadsorbent includes a member selected from the group consisting ofgranular, pellet, spherical, honeycomb, monolith, pelletizedcylindrical, particulate media of uniform shape, particulate media ofnon-uniform shape, structured media of extruded form, structured mediaof wound form, structured media of folded form, structured media ofpleated form, structured media of corrugated form, structured media ofpoured form, structured media of bonded form, non-wovens, wovens, sheet,paper, foam, hollow-cylinder, star, twisted spiral, asterisk, configuredribbons, and combinations thereof.

In any of the aspects or embodiments described herein, the adsorbentvolumes comprise a volumetric diluent. In any of the aspects orembodiments described herein, the volumetric diluent includes a memberselected from the group consisting of inert spacer particles, trappedair spaces, foams, fibers, screens, and combinations thereof.

In any of the aspects or embodiments described herein, the canistersystem further comprises a heat unit.

While several embodiments of the invention have been shown and describedherein, it will be understood that such embodiments are provided by wayof example only. Numerous variations, changes and substitutions willoccur to those skilled in the art without departing from the spirit ofthe invention. Rather, the present disclosure is to cover allmodifications, equivalents, and alternatives falling within the scope ofthe present disclosure as defined by the following appended claims andtheir legal equivalents. Accordingly, it is intended that thedescription and appended claims cover all such variations as fall withinthe spirit and scope of the invention.

In one embodiment, described is an evaporative emission control canistersystem comprising one or more canisters having a plurality of chambers,each chamber defining a volume, which are in fluid communicationallowing a fluid or vapor to flow directionally from one chamber to thenext, and at least one chamber comprises at least one particulateadsorbent volume, wherein the at least one particulate adsorbent volumeincludes a particulate adsorbent having microscopic pores with adiameter of less than about 100 nm, macroscopic pores having a diameterof about 100-100,000 nm, and a ratio of a volume of the macroscopicpores to a volume of the microscopic pores that is greater than about150%, and wherein the particulate adsorbent volume has a flowrestriction property of less than 40 Pa/cm under conditions of 46 cm/sapparent linear air flow velocity applied to a 43 mm diameter bed of theparticulate adsorbent material. In certain embodiments, the at least oneparticulate adsorbent volume has a flow restriction of less than 0.3 kPaunder 40 lpm air flow, a length to diameter ratio of 2 or more, or both.In certain embodiments, the particulate adsorbent volume has at leastone of: (i) a retentivity of less than 1.0 g/dL, (ii) a ratio of avolume of the macroscopic pores to a volume of the microscopic poresthat is greater than about 200%, or (iii) a length to diameter ratio of2 or more or (iv) a combination thereof. In certain embodiments, theparticulate adsorbent volume has a nominal butane working capacity of atleast 8 g/dL (e.g., at least 10 g/L), a nominal incremental adsorptioncapacity (IAC) at 25° C. of at least 35 g/L between vapor concentrationsof 5 vol % and 50 vol % n-butane, or both. In certain embodiments, thetwo-day diurnal breathing loss (DBL) is no more than 50 mg at no morethan 315 liters of purge applied after a 40 g/hr butane loading step asdetermined by the 2012 California Bleed Emissions Test Procedure (BETP).In certain embodiments, the two-day DBL is no more than 20 mg at no morethan 210 liters of purge applied after a 40 g/hr butane loading step asdetermined by the 2012 California Bleed Emissions Test Procedure (BETP).In certain embodiments, the two-day DBL is no more than 50 mg at no morethan 150 bed volumes of purge applied after a 40 g/hr butane loadingstep as determined by the 2012 California Bleed Emissions Test Procedure(BETP). In certain embodiments, the two-day DBL is no more than 20 mg atno more than 100 bed volumes of purge applied after a 40 g/hr butaneloading step as determined by the 2012 California Bleed Emissions TestProcedure (BETP). In certain embodiments, the evaporative emissioncontrol canister system comprises at least one fuel-side particulateadsorbent volume, at least one vent-side subsequent adsorbent volumes orboth. In certain embodiments, the particulate adsorbent volumes arelocated within a single canister or within a plurality of canisters thatare connected to permit sequential contact by the fuel vapor. In certainembodiments, the particulate adsorbent volume, the at least onevent-side subsequent adsorbent volume or both has a nominal BWC of lessthan 8 g/dL, a nominal IAC at 25 C of less than 35 g/L between vaporconcentrations of 5 vol % and 50 vol % n-butane, or both. In certainembodiments, the at least one fuel-side adsorbent volume, the at leastone vent-side particulate adsorbent volume, the at least one vent-sidesubsequent adsorbent volume, or a combination thereof includes anadsorbent material selected from the group consisting of activatedcarbon, carbon charcoal, zeolites, clays, porous polymers, porousalumina, porous silica, molecular sieves, kaolin, titania, ceria, andcombinations thereof. In certain embodiments, the at least one vent-sidesubsequent adsorbent volume is an activated carbon honeycomb. In certainembodiments, the activated carbon is derived from a material including amember selected from the group consisting of wood, wood dust, woodflour, cotton linters, peat, coal, coconut, lignite, carbohydrates,petroleum pitch, petroleum coke, coal tar pitch, fruit pits, fruitstones, nut shells, nut pits, sawdust, palm, vegetables, syntheticpolymer, natural polymer, lignocellulosic material, and combinationsthereof. In certain embodiments, the form of the adsorbent in the atleast one fuel-side adsorbent volume, the at least one vent-sidesubsequent adsorbent volume, or both includes a member selected from thegroup consisting of granular, pellet, spherical, honeycomb, monolith,pelletized cylindrical, particulate media of uniform shape, particulatemedia of non-uniform shape, structured media of extruded form,structured media of wound form, structured media of folded form,structured media of pleated form, structured media of corrugated form,structured media of poured form, structured media of bonded form,non-wovens, wovens, sheet, paper, foam, hollow-cylinder, star, twistedspiral, asterisk, configured ribbons, and combinations thereof. Incertain embodiments, the at least one vent-side subsequent adsorbentvolume includes a volumetric diluent. In certain embodiments, theevaporative emission control system comprises a heat unit. In certainembodiments, the vent-side particulate adsorbent volume has aretentivity of less than 0.5 g/dL.

In an additional embodiment, the description provides an evaporativeemission control canister system comprising: a fuel tank for storingfuel; an engine having an air induction system and adapted to consumethe fuel; an evaporative emission control canister system including oneor more canisters comprising a plurality of adsorbent volumes includingat least one fuel-side adsorbent volume; and at least one vent-sideparticulate adsorbent volume comprising a particulate adsorbent havingmicroscopic pores with a diameter of less than about 100 nm, macroscopicpores having a diameter of about 100-100,000 nm, a ratio of a volume ofthe macroscopic pores to a volume of the microscopic pores that isgreater than about 150%, and a retentivity of about 0.5 g/dL or less; afuel vapor inlet conduit connecting the evaporative emission controlcanister system to the fuel tank; a fuel vapor purge conduit connectingthe evaporative emission control canister system to the air inductionsystem of the engine; and a vent port for venting the evaporativeemission control canister system and for admission of purge air to theevaporative emission control canister system, wherein the evaporativeemission control canister system is defined by: a fuel vapor flow pathfrom the fuel vapor inlet conduit through a plurality of adsorbents tothe vent port, and an air flow path from the vent port through theplurality of adsorbent volumes and the fuel vapor purge outlet. Incertain embodiments, the evaporative emission control system furthercomprises at least one vent-side subsequent adsorbent volume upstream,downstream or both from the vent-side particulate adsorbent volume.

The contents of all references, patents, pending patent applications andpublished patents, cited throughout this application are herebyexpressly incorporated by reference.

Those skilled in the art will recognize, or be able to ascertain usingno more than routine experimentation, many equivalents to the specificembodiments of the invention described herein. Such equivalents areintended to be encompassed by the following claims. It is understoodthat the detailed examples and embodiments described herein are given byway of example for illustrative purposes only, and are in no wayconsidered to be limiting to the invention. Various modifications orchanges in light thereof will be suggested to persons skilled in the artand are included within the spirit and purview of this application andare considered within the scope of the appended claims. For example, therelative quantities of the ingredients may be varied to optimize thedesired effects, additional ingredients may be added, and/or similaringredients may be substituted for one or more of the ingredientsdescribed. Additional advantageous features and functionalitiesassociated with the systems, methods, and processes of the presentinvention will be apparent from the appended claims. Moreover, thoseskilled in the art will recognize, or be able to ascertain using no morethan routine experimentation, many equivalents to the specificembodiments of the invention described herein. Such equivalents areintended to be encompassed by the following claims.

What is claimed is:
 1. An evaporative emission control canister systemincluding one or more canisters comprising: at least one fuel-sideadsorbent volume; and at least one vent-side particulate adsorbentvolume comprising a particulate adsorbent having microscopic pores witha diameter of less than about 100 nm, macroscopic pores having adiameter of about 100-100,000 nm, and a ratio of the volume of themacroscopic pores to the volume of the microscopic pores that is greaterthan about 150%, wherein the vent-side adsorbent volume has a flowrestriction property of less than 40 Pa/cm pressure drop when a 46 cm/sapparent linear air flow velocity is applied to a 43 mm diameter bed ofthe vent-side particulate adsorbent volume, and at least one of (i) anominal butane working capacity (BWC) of <8 g/dL, (ii) a retentivity ofless than about 2 g/dL or (iii) a combination thereof.
 2. Theevaporative emission control canister system of claim 1, wherein the atleast one vent-side particulate adsorbent volume has a flow restrictionof less than 0.3 kPa under 40 lpm air flow.
 3. The evaporative emissioncontrol canister system of claim 1, wherein the vent-side particulateadsorbent volume has at least one of: (i) a retentivity of less than 1.0g/dL, (ii) a ratio of a volume of the macroscopic pores to a volume ofthe microscopic pores that is greater than about 200%, (iii) a length todiameter ratio of 2 or more or (iv) a combination thereof.
 4. Theevaporative emission control canister system of claim 1, wherein the atleast one fuel-side adsorbent volume has a nominal butane workingcapacity of at least 8 g/dL, a nominal incremental adsorption capacity(IAC) at 25 C of at least 35 g/L between vapor concentrations of 5 vol %and 50 vol % n-butane, or both.
 5. The evaporative emission controlcanister system of claim 1, wherein the two-day diurnal breathing loss(DBL) is no more than 50 mg at no more than 315 liters of purge appliedafter a 40 g/hr butane loading step as determined by the 2012 CaliforniaBleed Emissions Test Procedure (BETP).
 6. The evaporative emissioncontrol canister system of claim 5, wherein the two-day DBL is no morethan 20 mg at no more than 210 liters of purge applied after a 40 g/hrbutane loading step as determined by the 2012 California Bleed EmissionsTest Procedure (BETP).
 7. The evaporative emission control canistersystem of claim 1, wherein the two-day DBL is no more than 50 mg at nomore than 150 bed volumes of purge applied after a 40 g/hr butaneloading step as determined by the 2012 California Bleed Emissions TestProcedure (BETP).
 8. The evaporative emission control canister system ofclaim 7, wherein the two-day DBL is no more than 20 mg at no more than100 bed volumes of purge applied after a 40 g/hr butane loading step asdetermined by the 2012 California Bleed Emissions Test Procedure (BETP).9. The evaporative emission control canister system of claim 4, whereinthe adsorbent volumes are located within a single canister or within aplurality of canisters that are connected to permit sequential contactby the fuel vapor.
 10. The evaporative emission control canister systemof claim 1, comprising a single vent-side particulate adsorbent volume.11. The evaporative emission control canister system of claim 1,comprising multiple vent-side particulate adsorbent volumes.
 12. Theevaporative emission control canister system of claim 1, furthercomprising at least one vent-side subsequent adsorbent volume, whereinthe at least one vent-side subsequent adsorbent volume has a nominal BWCof less than 8 g/dL, a nominal IAC at 25 C of less than 35 g/L betweenvapor concentrations of 5 vol % and 50 vol % n-butane, or both.
 13. Theevaporative emission control canister system of claim 12, wherein the atleast one fuel-side adsorbent volume, the at least one vent-sideparticulate adsorbent volume, the at least one vent-side subsequentadsorbent volume, or a combination thereof includes an adsorbentmaterial selected from the group consisting of activated carbon, carboncharcoal, zeolites, clays, porous polymers, porous alumina, poroussilica, molecular sieves, kaolin, titania, ceria, and combinationsthereof.
 14. The evaporative emission control canister system of claim13, wherein the at least one vent-side subsequent adsorbent volume is anactivated carbon honeycomb.
 15. The evaporative emission controlcanister system of claim 13, wherein the activated carbon is derivedfrom a material including a member selected from the group consisting ofwood, wood dust, wood flour, cotton linters, peat, coal, coconut,lignite, carbohydrates, petroleum pitch, petroleum coke, coal tar pitch,fruit pits, fruit stones, nut shells, nut pits, sawdust, palm,vegetables, synthetic polymer, natural polymer, lignocellulosicmaterial, and combinations thereof.
 16. The evaporative emission controlcanister system of claim 13, wherein a form of the adsorbent in the atleast one fuel-side adsorbent volume, the at least one vent-sidesubsequent adsorbent volume, or both includes a member selected from thegroup consisting of granular, pellet, spherical, honeycomb, monolith,pelletized cylindrical, particulate media of uniform shape, particulatemedia of non-uniform shape, structured media of extruded form,structured media of wound form, structured media of folded form,structured media of pleated form, structured media of corrugated form,structured media of poured form, structured media of bonded form,non-wovens, wovens, sheet, paper, foam, hollow-cylinder, star, twistedspiral, asterisk, configured ribbons, and combinations thereof.
 17. Theevaporative emission control canister system of claim 12, wherein the atleast one vent-side subsequent adsorbent volume includes a volumetricdiluent.
 18. The evaporative emission control canister system of claim17, wherein the volumetric diluent includes a member selected from thegroup consisting of inert spacer particles, trapped air spaces, foams,fibers, screens, and combinations thereof.
 19. The evaporative emissioncontrol system of claim 1, further comprising a heat unit.
 20. Theevaporative emission control canister system of claim 1, wherein thevent-side particulate adsorbent volume has a retentivity of less than0.5 g/dL.
 21. An evaporative emission control canister system includingone or more canisters comprising: at least one fuel-side adsorbentvolume; and at least one vent-side low retentivity particulate adsorbentvolume comprising a particulate adsorbent having microscopic pores witha diameter of less than about 100 nm, macroscopic pores having adiameter of about 100-100,000 nm, and a ratio of the volume of themacroscopic pores to the volume of the microscopic pores that is greaterthan about 150%, wherein the at least one vent-side low retentivityparticulate adsorbent volume has a butane retentivity of less than 0.5g/dL.
 22. The evaporative emission control canister system of claim 21,wherein the at least one vent-side particulate adsorbent volume has aflow restriction property of less than 40 Pa/cm pressure drop underconditions of 46 cm/s apparent linear air flow velocity applied to a 43mm diameter bed of the vent-side particulate adsorbent volume.
 23. Theevaporative emission control canister system of claim 21, wherein thevent-side particulate adsorbent volume has at least one of: (i) aretentivity of less than 0.4 g/dL, (ii) a ratio of a volume of themacroscopic pores to a volume of the microscopic pores that is greaterthan about 200%, (iii) a length to diameter ratio of 2 or more or (iv) acombination thereof.
 24. The evaporative emission control canistersystem of claim 21, wherein the at least one fuel-side adsorbent volumehas at least one of (i) a nominal butane working capacity of at least 8g/dL, (ii) a nominal incremental adsorption capacity (IAC) at 25 C of atleast 35 g/L between vapor concentrations of 5 vol % and 50 vol %n-butane, or (iii) both.
 25. The evaporative emission control canistersystem of claim 24, wherein the two-day diurnal breathing loss (DBL) isno more than 50 mg at no more than 315 liters of purge applied after a40 g/hr butane loading step as determined by the 2012 California BleedEmissions Test Procedure (BETP).
 26. The evaporative emission controlcanister system of claim 25, wherein the two-day DBL is no more than 20mg at no more than 210 liters of purge applied after a 40 g/hr butaneloading step as determined by the 2012 California Bleed Emissions TestProcedure (BETP).
 27. The evaporative emission control canister systemof claim 24, wherein the two-day DBL is no more than 50 mg at no morethan 150 bed volumes of purge applied after a 40 g/hr butane loadingstep as determined by the 2012 California Bleed Emissions Test Procedure(BETP).
 28. The evaporative emission control canister system of claim27, wherein the two-day DBL is no more than 20 mg at no more than 100bed volumes of purge applied after a 40 g/hr butane loading step asdetermined by the 2012 California Bleed Emissions Test Procedure (BETP).29. The evaporative emission control canister system of claim 21,wherein the adsorbent volumes are located within a single canister orwithin a plurality of canisters that are connected to permit sequentialcontact by the fuel vapor.
 30. The evaporative emission control canistersystem of claim 21, comprising a single vent-side particulate adsorbentvolume.
 31. The evaporative emission control canister system of claim21, comprising multiple vent-side particulate adsorbent volumes.
 32. Theevaporative emission control canister system of claim 21, furthercomprising at least one vent-side subsequent adsorbent volume, whereinthe at least one vent-side subsequent adsorbent volume has a nominal BWCof less than 8 g/dL, a nominal IAC at 25 C of less than 35 g/L betweenvapor concentrations of 5 vol % and 50 vol % n-butane, or both.
 33. Theevaporative emission control canister system of claim 32, wherein the atleast one fuel-side adsorbent volume, the at least one vent-sideparticulate adsorbent volume, the at least one vent-side subsequentadsorbent volume, or a combination thereof includes an adsorbentmaterial selected from the group consisting of activated carbon, carboncharcoal, zeolites, clays, porous polymers, porous alumina, poroussilica, molecular sieves, kaolin, titania, ceria, and combinationsthereof.
 34. The evaporative emission control canister system of claim33, wherein the at least one vent-side subsequent adsorbent volume is anactivated carbon honeycomb.
 35. The evaporative emission controlcanister system of claim 33, wherein the activated carbon is derivedfrom a material including a member selected from the group consisting ofwood, wood dust, wood flour, cotton linters, peat, coal, coconut,lignite, carbohydrates, petroleum pitch, petroleum coke, coal tar pitch,fruit pits, fruit stones, nut shells, nut pits, sawdust, palm,vegetables, synthetic polymer, natural polymer, lignocellulosicmaterial, and combinations thereof.
 36. The evaporative emission controlcanister system of claim 33, wherein a form of the adsorbent in the atleast one fuel-side adsorbent volume, the at least one vent-sidesubsequent adsorbent volume, or both includes a member selected from thegroup consisting of granular, pellet, spherical, honeycomb, monolith,pelletized cylindrical, particulate media of uniform shape, particulatemedia of non-uniform shape, structured media of extruded form,structured media of wound form, structured media of folded form,structured media of pleated form, structured media of corrugated form,structured media of poured form, structured media of bonded form,non-wovens, wovens, sheet, paper, foam, hollow-cylinder, star, twistedspiral, asterisk, configured ribbons, and combinations thereof.
 37. Theevaporative emission control canister system of claim 32, wherein the atleast one vent-side subsequent adsorbent volume includes a volumetricdiluent.
 38. The evaporative emission control canister system of claim37, wherein the volumetric diluent includes a member selected from thegroup consisting of inert spacer particles, trapped air spaces, foams,fibers, screens, and combinations thereof.
 39. The evaporative emissioncontrol system of claim 21, further comprising a heat unit.
 40. Theevaporative emission control canister system of claim 21, wherein thevent-side particulate adsorbent volume has a retentivity of less than0.25 g/dL.
 41. An evaporative emission control canister system includingone or more canisters comprising: at least one fuel-side adsorbentvolume; and at least one vent-side low retentivity particulate adsorbentvolume comprising a particulate adsorbent having microscopic pores witha diameter of less than about 100 nm, macroscopic pores having adiameter of about 100-100,000 nm, a ratio of the volume of themacroscopic pores to the volume of the microscopic pores that is greaterthan about 200%, and wherein the at least one vent-side particulateadsorbent volume has a butane retentivity of less than 1 g/dL.
 42. Theevaporative emission control canister system of claim 41, wherein the atleast one vent-side particulate adsorbent volume has a flow restrictionproperty of less than 40 Pa/cm pressure drop under conditions of 46 cm/sapparent linear air flow velocity applied to a 43 mm diameter bed of thevent-side particulate adsorbent volume.
 43. The evaporative emissioncontrol canister system of claim 41, wherein the vent-side particulateadsorbent volume has at least one of: (i) a retentivity of less than 1.0g/dL, (ii) a ratio of a volume of the macroscopic pores to a volume ofthe microscopic pores that is greater than about 200%, (iii) a length todiameter ratio of 2 or more or (iv) a combination thereof.
 44. Theevaporative emission control canister system of claim 41, wherein the atleast one fuel-side adsorbent volume has a nominal butane workingcapacity of at least 8 g/dL, a nominal incremental adsorption capacity(IAC) at 25 C of at least 35 g/L between vapor concentrations of 5 vol %and 50 vol % n-butane, or both.
 45. The evaporative emission controlcanister system of claim 44, wherein the two-day diurnal breathing loss(DBL) is no more than 50 mg at no more than 315 liters of purge appliedafter a 40 g/hr butane loading step as determined by the 2012 CaliforniaBleed Emissions Test Procedure (BETP).
 46. The evaporative emissioncontrol canister system of claim 45, wherein the two-day DBL is no morethan 20 mg at no more than 210 liters of purge applied after a 40 g/hrbutane loading step as determined by the 2012 California Bleed EmissionsTest Procedure (BETP).
 47. The evaporative emission control canistersystem of claim 44, wherein the two-day DBL is no more than 50 mg at nomore than 150 bed volumes of purge applied after a 40 g/hr butaneloading step as determined by the 2012 California Bleed Emissions TestProcedure (BETP).
 48. The evaporative emission control canister systemof claim 47, wherein the two-day DBL is no more than 20 mg at no morethan 100 bed volumes of purge applied after a 40 g/hr butane loadingstep as determined by the 2012 California Bleed Emissions Test Procedure(BETP).
 49. The evaporative emission control canister system of claim41, wherein the adsorbent volumes are located within a single canisteror within a plurality of canisters that are connected to permitsequential contact by the fuel vapor.
 50. The evaporative emissioncontrol canister system of claim 41, comprising a single vent-sideparticulate adsorbent volume.
 51. The evaporative emission controlcanister system of claim 41, comprising multiple vent-side particulateadsorbent volumes.
 52. The evaporative emission control canister systemof claim 41, further comprising at least one vent-side subsequentadsorbent volume, wherein the at least one vent-side subsequentadsorbent volume has a nominal BWC of less than 8 g/dL, a nominal IAC at25 C of less than 35 g/L between vapor concentrations of 5 vol % and 50vol % n-butane, or both.
 53. The evaporative emission control canistersystem of claim 42, wherein the at least one fuel-side adsorbent volume,the at least one vent-side particulate adsorbent volume, the at leastone vent-side subsequent adsorbent volume, or a combination thereofincludes an adsorbent material selected from the group consisting ofactivated carbon, carbon charcoal, zeolites, clays, porous polymers,porous alumina, porous silica, molecular sieves, kaolin, titania, ceria,and combinations thereof.
 54. The evaporative emission control canistersystem of claim 53, wherein the at least one vent-side subsequentadsorbent volume is an activated carbon honeycomb.
 55. The evaporativeemission control canister system of claim 53, wherein the activatedcarbon is derived from a material including a member selected from thegroup consisting of wood, wood dust, wood flour, cotton linters, peat,coal, coconut, lignite, carbohydrates, petroleum pitch, petroleum coke,coal tar pitch, fruit pits, fruit stones, nut shells, nut pits, sawdust,palm, vegetables, synthetic polymer, natural polymer, lignocellulosicmaterial, and combinations thereof.
 56. The evaporative emission controlcanister system of claim 53, wherein a form of the adsorbent in the atleast one fuel-side adsorbent volume, the at least one vent-sidesubsequent adsorbent volume, or both includes a member selected from thegroup consisting of granular, pellet, spherical, honeycomb, monolith,pelletized cylindrical, particulate media of uniform shape, particulatemedia of non-uniform shape, structured media of extruded form,structured media of wound form, structured media of folded form,structured media of pleated form, structured media of corrugated form,structured media of poured form, structured media of bonded form,non-wovens, wovens, sheet, paper, foam, hollow-cylinder, star, twistedspiral, asterisk, configured ribbons, and combinations thereof.
 57. Theevaporative emission control canister system of claim 52, wherein the atleast one vent-side subsequent adsorbent volume includes a volumetricdiluent.
 58. The evaporative emission control canister system of claim57, wherein the volumetric diluent includes a member selected from thegroup consisting of inert spacer particles, trapped air spaces, foams,fibers, screens, and combinations thereof.
 59. The evaporative emissioncontrol system of claim 41, further comprising a heat unit.
 60. Theevaporative emission control canister system of claim 41, wherein thevent-side particulate adsorbent volume has a retentivity of less than0.5 g/dL.